Patent Publication Number: US-9848605-B2

Title: Bait materials, pest monitoring devices and other pest control devices that include polyurethane foam

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 12/583,259 filed on 18 Aug. 2009, which claims the benefit of U.S. Provisional Patent Application No. 61/189,379 filed on 19 Aug. 2008, each of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present application relates to pest control, and more particularly, relates to techniques for using a polyurethane foam in a bait material and/or in a monitoring device or other termite control device. 
     The removal of pests from areas occupied by humans, livestock, and crops has long been a challenge. Pests of frequent concern include various types of insects and rodents. Subterranean termites are a particularly troublesome type of pest with the potential to cause severe damage to wooden structures. Various schemes have been proposed to eliminate termites and certain other harmful pests of both the insect and noninsect variety. In one approach, pest control relies on the blanket application of chemical pesticides in the area to be protected. However, this approach is becoming less desirable than targeted pesticide delivery, which can be more efficient and environmentally friendly. 
     Recently, advances have been made to provide for the targeted delivery of pesticide chemicals. U.S. Pat. No. 5,815,090 to Su is one example. Another example directed to termite control is the SENTRICON TERMITE COLONY ELIMINATION SYSTEM™ of Dow AgroSciences LLC that has a business address of 9330 Zionsville Road, Indianapolis, Ind. In this system, a number of units each having a termite edible material, are placed in the ground about a dwelling to be protected. The units are inspected routinely by a pest control service for the presence of termites, and inspection data is recorded with reference to a unique barcode label associated with each unit. If termites are found in a given unit, a bait is installed that contains a slow-acting pesticide intended to be carried back to the termite nest to eradicate the colony. U.S. Pat. Nos. 6,724,312; 7,212,112; and 7,212,129; and U.S. Patent Application Publication Nos. 2001/0033230 and 2001/0054962 provide further examples. 
     In certain instances, the bait in an in-ground pest control device, such as a monitoring device or a pesticide delivery device, degrades with prolonged exposure to moisture, which can undermine its appeal to targeted pests, and sometimes results in improper operation of associated sensors (if present). Frequently, it is desirable to maintain the palatability of the bait in a pest control device over a longer period of time and/or better control moisture intrusion. In other instances, the bait in an above-ground pest control devices loses its appeal to target pests when it becomes dried, which can undermine its efficacy to eradicate a termite colony. In addition, currently available above-ground pest control devices utilize preferred texture cellulose (PTC) bait materials, which are contained in a polyethylene bag that is cut open for termite entry. When termites feed on the PTC in the bag, they also typically impart significant damage to the bag so that the PTC spills from the above-ground station when it is opened, causing a significant mess and inconvenience for users. Thus, there is a demand for further contributions in this area of technology. 
     SUMMARY 
     One embodiment of the present application is a unique technique for pest control. Other embodiments include unique apparatus, systems, methods, materials and devices to protect bait in an in-ground pest control device, such as a monitoring device or a pesticide delivery device, from moisture intrusion or the like. Still other embodiments include unique apparatus, systems, methods, materials and devices to protect an above-ground bait from becoming desiccated. Further embodiments, forms, features and aspects shall become apparent from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a diagrammatic view of a composite bait material according to one embodiment of the present application. 
         FIG. 2  is a cross sectional view of a composite bait material according to another embodiment of the present application. 
         FIG. 3  is a diagrammatic view of a pest control system according to the present application that includes several pest control devices. 
         FIG. 4  is a further view of selected aspects of the system of  FIG. 3  in operation. 
         FIG. 5  is a partial, exploded sectional view of a pest monitoring assembly of one of the pest control devices. 
         FIG. 6  is a partial, exploded sectional view of the pest monitoring assembly of  FIG. 5  along a view plane perpendicular to the view plane of  FIG. 5 . 
         FIG. 7  is a partial, top view of a portion of a communication circuit subassembly of the pest monitoring assembly shown in  FIGS. 5 and 6 . 
         FIG. 8  is an exploded view of a bait container of one of the pest control devices of the pest control system depicted in  FIG. 3 , including the pest monitoring assembly of  FIG. 5 . 
         FIG. 9  is a perspective exploded view of the pest control device assembly of  FIG. 8  with a diagrammatic cut away of the bait container and a diagrammatic cut away of the composite bait material, and further showing a ground installable housing of one of the pest control devices. 
         FIG. 10  is a side, diagrammatic partial sectional, partial cutaway view of the assembly of  FIG. 9 . 
         FIG. 11  is a schematic view of communication circuitry included in the pest control device of  FIG. 8  and communication circuitry included the interrogator shown in  FIGS. 3 and 4 . 
         FIG. 12  is an exploded view of another embodiment bait container that can be used as a stand alone pest monitoring device or as one of the pest control devices of the pest control system depicted in  FIG. 3 , including the pest monitoring assembly of  FIG. 5 . 
         FIG. 13  is a perspective exploded view of the pest control device assembly of  FIG. 12  with a diagrammatic cut away of the bait container and further showing a ground installable housing of one of the pest control devices. 
         FIG. 14  is a side, diagrammatic partial sectional, partial cutaway view of the assembly of  FIG. 13 . 
         FIG. 15  is a side view of a fitting that can optionally be used with a modified version of the bait container depicted in  FIG. 12 . 
         FIG. 16  is a top plan view of the fitting shown in  FIG. 15 . 
         FIG. 17  is a partially sectional perspective view of another embodiment of a pest monitoring device that can be used as a stand alone pest monitoring device or as one of the pest control devices in the pest control system depicted in  FIG. 3 , including the pest monitoring assembly of  FIG. 5 . 
         FIG. 18  is a partially sectional perspective view of yet another embodiment of a pest monitoring device that can be used as a stand alone pest monitoring device or as one of the pest control devices in the pest control system depicted in  FIG. 3 , including the pest monitoring assembly of  FIG. 5 . 
         FIG. 19  depicts another embodiment bait container that can be used in a pest control device or as a stand alone bait. 
         FIG. 20  depicts an above-ground bait station that includes a composite bait material therein. 
     
    
    
     DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS 
     For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     The present application relates to the inclusion of a polyurethane foam in a bait material or in a termite control device, such as, for example a monitoring device or pesticide delivery device. The terms “bait” and “bait material” are used interchangeably herein to refer to a material that is attractive to termites, including, for example, a material that is edible by the termites, a material that includes chemical or biochemical agents that attract termites, and/or a material that is otherwise effective to attract termites, whether or not the material includes a pesticide and whether the material is used in an monitoring device, a pesticide delivery device or other termite control device. The polyurethane foam can provide a variety of functions when included in a bait material or in a termite control device. For example, in one embodiment a closed-cell or properly selected open-cell polyurethane foam can be used to provide a moisture barrier protecting a cellulosic food material in a bait material or in an in-ground pest control device, thereby maintaining palatability of the bait over an extended period of time. In another embodiment, an open-cell polyurethane foam can be used to provide a structural matrix for a cellulosic food material to hold moisture in contact with the food material in an above-ground pest control device to make the food material more attractive to termites. The polyurethane foam can also operate to hold a bait material together to prevent crumbling and spilling of the bait, such as commonly occurs when an above-ground station containing a conventional bait material is opened. 
     In one aspect, the application provides a moisture-resistant composite bait material that is operable to be consumed or displaced by one or more species of termites. With reference to the embodiment depicted in  FIG. 1 , composite bait material  1  includes a plurality of cellulosic food material pieces  2  that are palatable to the termite species, embedded within a termite-edible or termite-displaceable polyurethane foam matrix  3 . In some uses of a termite bait, it is desirable to attract termites to a bait material without delivering a pesticide. One example is a bait intended for use in a monitoring device to monitor an area for the presence of termites. Such a bait material can be observed periodically to determine whether termites are actively feeding in the area. Multiple examples of the use of a composite bait material in a monitoring device are described further hereinbelow. In other uses of a termite bait, it is desirable to attract termites and to deliver a pesticide to the termites attracted to the bait. A bait used in this manner can include a pesticide in the bait material. The term “pesticide” is used herein to refer to a compound that is toxic to at least one target species of termites. In an embodiment that includes a pesticide, the pesticide retains its bioactivity as it resides within composite bait material  1 , and produces a desired result after the material is ingested by or otherwise comes into contact with termites as composite bait material  1  is consumed or displaced by the termites. 
     In one embodiment, foam matrix  3  is composed of a closed-cell polyurethane foam. In this embodiment, foam matrix  3  provides a water resistant barrier surrounding at least one, and preferably most or all, of cellulosic food material pieces  2 . In certain embodiments, foam matrix  3  separately encapsulates, or compartmentalizes, some or all of the cellulosic food material pieces, which increases the operational life of bait material pieces  2 , even when bait material  1  is exposed to moisture, and even after some of matrix  3  is consumed by termites or otherwise breached. In such embodiments, after a portion of the bait matrix is consumed or breached, the remaining portions of foam matrix  3  continue to functionally protect the remainder of the cellulosic food material pieces that remain encapsulated by foam matrix  3 . The bait material of this embodiment is useful in situations where it is desirable for the bait to withstand exposure to moist conditions without becoming fouled for an extended period of time. 
     In another embodiment, foam matrix  3  is composed of an open-cell polyurethane foam, and operates to hold moisture in contact with food material pieces  2 . A bait material of this embodiment is useful in situations where it is desirable for food material pieces  2  to be kept in a moistened state for an extended period of time, such as, for example, for use in an above-ground termite control station, as will be described further hereinbelow. 
     In one embodiment, cellulosic food material pieces  2  are selected based upon known or measured attractability for termites. The cellulosic food material therefore attracts members of a termite colony and would be expected to be consumed or displaced by the termites. In one embodiment, the cellulosic food material pieces are cellulose briquettes, such as, for example, RECRUIT IV™ cellulose briquettes, which are commercially available from Dow Agrosciences LLC (Indianapolis, Ind.). In other embodiments, other cellulose briquettes or other cellulose-containing materials, with or without a pesticide contained therein, can be used. In one embodiment, the food material is composed in whole or in part of an edible plastic material, which can include cellulose therein (referred to as a “cellulose plus plastic” material). For example, cellulosic food material pieces  2  can be composed of a material including a thermoplastic polymer, such as, for example, a material made as described in the commonly-owned U.S. Patent Application Publication No. 2008/0187565, which is hereby incorporated by reference herein in its entirety. For example, cellulosic food material pieces  2  can be made by molding, extruding or otherwise processing a termite-edible thermoplastic material or a mixture of a thermoplastic material and a pest food material, with or without a pesticide included therein. A material including a thermoplastic polymer can be molded into predetermined shapes and sizes for use as food material pieces  2 , or can optionally be formed into a larger workpiece from which food material pieces  2  having desired sizes and shapes can be obtained, for example, by cutting, breaking, grinding, machining or otherwise processing the workpiece into food material pieces. The present application also contemplates, particularly in connection with embodiments in which food material pieces  2  are provided by breaking or grinding a larger workpiece, that the process can also include one or more screening steps to separate particles and/or pieces into desired size fractions. 
     In another embodiment, the food material is a purified cellulose, such as, for example, alpha cellulose, beta cellulose or gamma cellulose. One suitable example is preferred texture cellulose (PTC). Cellulosic food material pieces having a wide variety of sizes and shapes can be made from cellulose particles, for example, by compacting the cellulose and breaking the compacted material into prills. In addition, pre-formed prills of cellulose are available commercially, and can be obtained from International Fiber Corporation (North Tonawanda, N.Y.). In other embodiments, the food material is wood or a derivative of wood, such as, for example, wood chips, wood fibers, sawdust, cardboard, paper or other material that is palatable to a target wood-destroying species. Such materials can be provided in a wide variety of sizes and shapes. Other cellulosic food materials that can be employed include microcrystalline cellulose, examples of which are provided in U.S. Pat. No. 6,416,752, which is incorporated herein by reference, and modified polymeric cellulose based materials such as, for example, METHOCEL® or ETHOCEL®, which are available commercially from The Dow Chemical Company (Midland, Mich.). The present application also contemplates that a variety of different types of food material can be included in the composite bait material. 
     Polyurethane foam matrix  3  is displaced or consumed by termites, and therefore does not prevent termites from tunneling to and feeding on the cellulosic food material pieces. Polyurethane foam matrix  3  can be made to have a wide variety of properties for producing composite bait materials having a wide variety of physical features. For example, polyurethane foam matrix  3  can be made in an open-cell or closed-cell configuration, can be made to exhibit varying degrees of rigidity/flexibility, and can be made to have a wide variety of densities. It can also be formed to incorporate one or more termite feeding enhancer, such as, for example, a cellulose in a powder form, a sugar or a chemical or biochemical termite attractant into the polyurethane foam to increase termite penetration, as discussed further hereinbelow. 
     In one manner of making a composite bait material, a plurality of pieces of a cellulosic food material are provided in a bait enclosure so that the bait enclosure and the plurality of cellulosic food material pieces define a void space therebetween. The bait enclosure can be, for example, a bait tube configured for placement in a bait station, as described in further detail hereinbelow, or can be a mold that is used temporarily for the purpose of making a composite bait material article of a given shape. A mold would be used, for example, to make a bait material that is desired to be used as a stand-alone bait material or to be later inserted into a bait container. In an embodiment for use as a stand-alone bait material, polyurethane foam matrix  3  provides sufficient strength and structural integrity for a desired end use of composite bait material  1 , even in the absence of a bait container. 
     With the pieces of a cellulosic food material positioned in the bait enclosure, an uncured mixture of polyurethane foam precursors is then introduced into the bait enclosure such that the mixture enters at least some of the void space. The mixture is then allowed to cure to provide a polyurethane foam barrier surrounding at least one, and preferably most or all, of the plurality of cellulosic food material pieces. The uncured mixture of polyurethane foam precursors includes at least one diisocyanate or polyisocyanate (referred to collectively herein as “isocyanate molecules” or “isocyanates”) and at least one polyol. Polyurethane foam matrix  3  is produced via reaction of isocyanate molecules and polyol molecules. While the reaction is exothermic, the curing process does not produce an excessive amount of heat that would damage the cellulosic food material pieces, pesticides, or other materials present in the composite material. In certain preferred embodiments, the curing process, during which the precursors react to form polyurethane foam, is accompanied by expansion of the mixture as it undergoes the curing reaction. In one embodiment, for example, the mixture of polyurethane precursors includes water, which reacts with isocyanates in the mixture to produce carbon dioxide, which expands the mixture and causes the mixture to move into additional portions of the void space. A polyurethane foam that expands by the generation of carbon dioxide is referred to herein as a “self-expanding foam.” One or more vent holes can be provided in the bait enclosure, if desired, to allow for release of pressure within the bait enclosure as the mixture cures, and for excess material to escape the bait enclosure as it expands during curing. 
     Many different kinds of polyurethane materials can be produced from a few types of isocyanates and a range of polyols with different functionality and molecular weights. Some of the diversity of polyurethane foam materials depends on whether the polyols used to make a given polyurethane foam are based on polyether or polyesters, both of which are contemplated by the present application. In one embodiment, foam matrix  3  is made from a mixture of precursor ingredients that includes at least one polyether polyol. Polyether polyols include the repeating ether linkage —R—O—R— and have two or more hydroxyl groups as terminal functional groups. Polyether polyols are produced by the oxyalkylation of discrete polyfunctional initiators (also referred to as “starters”). They are manufactured commercially by the catalyzed addition of epoxies (cyclic ethers), such as, for example, propylene oxide, ethylene oxide or butylene oxide, to active hydrogen-containing initiator compounds, such as, for example, glycerin, trimethylolpropane, pentaerythritol, sucrose, sorbitol, water, bisphenol A, ethylenediamine, toluenediamine, ethylene glycol, and propylene glycol; thus, a wide variety of compositions of varying structures, chain lengths and molecular weights is possible. The physical properties of the polyols are influenced primarily by the functionality of the initiator molecules and by the type and quantity of alkylene oxide and hydroxyl groups present in the polyol. In general, the functionality of the polyether is carried over from the functionality of the initiator used. By selecting a certain oxide (or oxides), initiator, and reaction conditions and catalysts, it is possible to synthesize polyether polyols that range from low-molecular-weight polyglycols to high-molecular-weight resins. Since polyether polyols include repeating alkylene oxide units, they are often referred to as polyalkylene glycols or polyglycols. The terms “polyglycol” and “polyether polyol” are used interchangeably. Polyols of interest for polyurethane foams generally are based on initiators with a functionality (active hydrogen content) of three or higher. Flexible foams typically employ tri-functional polyols, while higher-functional polyols are typically used in the production of rigid foams. The following table lists a variety of commercially available polyether polyol types that can be used to make a polyurethane foam in accordance with the present application, plus initiators and cyclic ethers (oxides) that can be used in their preparation: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Selected Commercial Polyether Polyols and Reactants 
               
            
           
           
               
               
               
            
               
                 Product 
                 Initiator 
                 Cyclic Ether 
               
               
                   
               
               
                 Difunctional 
                   
                   
               
               
                 Polypropylene Glycol (PPG) 
                 Water or propylene glycol 
                 Propylene oxide 
               
               
                 Polyethylene Glycol (PEG) 
                 Water or ethylene glycol 
                 Ethylene oxide 
               
               
                 Polyoxypropylene-Polyoxy- 
                 Water, propylene glycol 
                 Propylene oxide and 
               
               
                 ethylene Block Copolymer 
                 or glycerin * 
                 ethylene oxide 
               
               
                 Polytetramethylene Ether 
                 Water 
                 Tetrahydrofuran 
               
               
                 Glycol (PTMEG) 
               
               
                 Aromatic Diol 
                 Bisphenol A 
                 Propylene oxide or 
               
               
                   
                   
                 ethylene oxide 
               
               
                 Amine Adducts 
                 Primary monoamines ** 
                 Propylene oxide or 
               
               
                   
                   
                 ethylene oxide 
               
               
                 Trifunctional 
               
               
                 Glycerin Adduct 
                 Glycerin 
                 Propylene oxide 
               
               
                 Trimethylolpropane Adduct 
                 Trimethylolpropane 
                 Propylene oxide 
               
               
                 Trimethylolethane Adduct 
                 Trimethylolethane 
                 Propylene oxide 
               
               
                 Tetrafunctional 
               
               
                 Pentaerythritol Adduct 
                 Pentaerythritol 
                 Propylene oxide 
               
               
                 Ethylenediamine Adduct 
                 Ethylenediamine 
                 Propylene oxide 
               
               
                 Phenolic Resin Adduct 
                 Phenolic resin 
                 Propylene oxide 
               
               
                 Methyl Glucoside Adduct 
                 Methyl Glucoside 
                 Propylene oxide 
               
               
                 Pentafunctional 
               
               
                 Diethylenetriamine Adduct 
                 Diethylenetriamine 
                 Propylene oxide 
               
               
                 Hexafunctional 
               
               
                 Sorbitol Adducts 
                 Sorbitol 
                 Propylene oxide or 
               
               
                   
                   
                 ethylene oxide 
               
               
                 Octafunctional 
               
               
                 Sucrose Adducts 
                 Sucrose 
                 Propylene oxide 
               
               
                   
               
               
                 * Other compounds, including trimethylolpropane, trimethylolethane, pentaerythritol, ethylenediamine, sorbitol and sucrose, can also be used as initiators for block copolymers based on propylene oxide and ethylene oxide. 
               
               
                 ** Primary monoamines include aniline, cyclohexylamine and others. The compositions made from these amines and oxides are principally surface-active agents. 
               
            
           
         
       
     
     The isocyanate used to make the polyurethane foam can be a diisocyanate, which includes two isocyanate groups, or a polyisocyanate, which includes three or more isocyanate groups, and may include several isocyanate groups. Suitable diisocyanates for use in the present application include, for example, methylene bis(phenyl isocyanate) (also referred to as “methylene diphenyl diisocyanate” or MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI), methylene bis-cyclohexylisocyanate (HMDI) (hydrogenated MDI), and isophorone diisocyanate (IPDI). Examples of suitable polyisocyanates include HDI biuret and HDI isocyanurate. The isocyanate group reacts with the hydroxyl functional group to form a urethane linkage. If a diisocyanate is reacted with a compound containing two or more hydroxyl groups (a polyol), long polymer chains are formed, producing polyurethanes. 
     In addition to the polyol and isocyanate components, the mixture of polyurethane foam precursors also optionally includes a catalyst. While some polyols have catalytic activity, and thus a separate catalyst can be omitted, a catalyst will typically be included to increase the rate of the curing reaction. A wide variety of polyurethane catalysts are described in the literature, and many are available commercially. It is well within the purview of a person of ordinary skill in the art to select a suitable catalyst for a given polyurethane foam formulation. In one embodiment, the catalyst is a metal complex, a metal salt or a tertiary amine. Examples of metal complexes that can be used include, without limitation, complexes of tin, zinc, bismuth and/or lead. Examples of metal salts that can be used include, without limitation, sodium salts and/or potassium salts. The catalyst is operable in various formulations for the purpose of blowing (i.e., catalyzing the reaction of water and isocyanate to produce carbon dioxide), gelling (i.e., catalyzing the reaction of the polyol and isocyanate to produce a polyurethane polymer) and/or isocyanate trimerization. Metal complex catalysts and metal salt catalysts, for example, effectively catalyze gelling and isocyanate trimerization reactions. Tertiary amine catalysts are effective for catalyzing blowing, gelling and isocyanate trimerization reactions. In one embodiment, the catalyst is bis(dimethylaminopropyl) methylamine, which is available commercially as the product POLYCAT 77®. 
     The mixture of polyurethane foam precursors can also optionally include a wide variety of additional ingredients, such as, for example and without limitation, a surfactant, a flame retardant, a blowing agent, a low molecular weight multifunctional alcohol, such as, for example, diethyl glycol, an inorganic filler, a pigment or dye, an antioxidant, a plasticizer, such as, for example, a phthalate ester, and/or an antimicrobial additive. Examples of these optional additives are well known in the art and are available commercially. 
     As stated above, in one embodiment the mixture of polyurethane precursors includes water in an amount effective to react with the isocyanate component to produce carbon dioxide during the curing reaction. The amount of water included in the mixture can be adjusted to modify the density of the resulting polyurethane foam. As will be appreciated by a person of ordinary skill in the art, the amount of carbon dioxide produced is directly related to the amount of water in the mixture (as long as sufficient isocyanate is present for the water to fully react), and the amount of carbon dioxide produced is inversely related to the density of the resulting polyurethane foam. In addition, the final density of polyurethane foam depends not only on the amount of carbon dioxide produced during the blowing reaction, but also upon how much the foam is confined during expansion. After the liquid mixture of polyurethane foam precursors is added to the bait container or mold and the curing reaction begins, the foam expands to fill the void space. As the foam expands, it becomes more viscous. Because the foam is at least partially confined in the mold or bait container during foam formation, its expansion is partially restrained, which causes increased pressure on the curing material, reducing the volume of space occupied by the carbon dioxide, and resulting in a final density that is greater than if the foam were allowed to expand without restraint. Therefore, by controlling the amount of blowing agent present and by controlling the degree to which expansion is restrained, the density of the final product can be controlled. In one embodiment, the polyurethane foam in the composite bait material has a density of from about 2 to about 6 pounds per cubic foot. In another embodiment, the polyurethane foam in the composite bait material has a density of from about 3 to about 5 pounds per cubic foot. In another embodiment, the polyurethane foam in the composite bait material has a density of from about 3.5 to about 4.5 pounds per cubic foot. In yet another embodiment, the polyurethane foam has a density of about 4 pounds per cubic foot. When making a composite bait material by curing the polyurethane foam in a bait tube sized to fit in a SENTRICON TERMITE COLONY ELIMINATION SYSTEM® bait station, or in a mold or bait enclosure of similar dimensions, it has been found that a mixture of polyurethane foam precursors that would produce a foam having a density of about 2 pounds per cubic foot in the absence of expansion resistance will produce a foam having a density of about 4 pounds per cubic foot as a result of the pressure in the bait tube resulting from resistance during flow of the curing foam through the void space. While the effect of pressure on final density is expected to differ for mixtures having different formulations of ingredients, it is within the purview of a person of ordinary skill in the art, in view of the descriptions herein and without undue experimentation, to select formulations and pressures to produce a polyurethane foam having a desired density. 
     The present application also contemplates that polyurethane foams can be made using alternative gaseous ingredients as blowing agents. For example, a mixture of polyurethane foam precursors can be provided in a delivery system that includes a gaseous blowing agent, such as for example, the GREAT STUFF™ polyurethane foam system that is commercially available from The Dow Chemical Company. In embodiments in which alternative gaseous ingredients are provided, the generation of carbon dioxide during the curing reaction is unnecessary, and water can be omitted from the mixture, or included in a lesser amount. 
     As will be appreciated by a person of ordinary skill in the art, it is important to prevent mixing of the polyol and isocyanate components, and also to prevent mixing of water with the isocyanate in self-expanding embodiments, until it is desired to initiate curing. For convenience, the polyol and isocyanate components are referred to herein as the first precursor component and second precursor component, respectively. When water is present, it is included with the polyol in the first precursor component so that the water and the polyol can be mixed with the isocyanate at the same time to initiate both reactions simultaneously. Additional ingredients (i.e., ingredients other than the polyol and isocyanate components), if present, can be mixed with either the first precursor component or the second precursor component prior to initiating cure. In one embodiment, the additional components, if present, are mixed with the first precursor component (i.e., the polyol component). In one embodiment, the polyol component comprises from about 50 to about 96 parts polyether polyol, from about 0.2 to about 6 parts surfactant, from about 0.05 to about 4 parts amine catalyst, from about 0.1 to about 20 parts water, and optionally also includes up to 96 parts polyester polyol, up to 2 parts metal based catalyst, up to 15 parts HFC blowing agent and/or up to 12 parts pentane blowing agent. At the time when it is desired to initiate curing, the first precursor component is mixed with the second precursor component (i.e., the isocyanate component), and the mixture is then placed in the void space for curing, as described above. 
     The proportion of cellulosic food material pieces  2  to foam matrix  3  in bait material  1  can vary. In one embodiment, the bait material includes an average of from about 5 to about 200 parts foam matrix to 100 parts cellulosic food material pieces, by weight. In another embodiment, the bait material includes an average of from about 5 to about 150 parts foam matrix to 100 parts cellulosic food material pieces, by weight. In yet another embodiment, the bait material includes an average of from about 5 to about 100 parts foam matrix to 100 parts cellulosic food material pieces, by weight. In still another embodiment, the bait material includes an average of from about 5 to about 50 parts foam matrix to 100 parts cellulosic food material pieces, by weight. In another embodiment, the bait material includes an average of from about 10 to about 40 parts foam matrix to 100 parts cellulosic food material pieces, by weight 
     In one representative example of a method for making a composite bait material, the material is made by providing a first precursor component that includes a polyol (or optionally a mixture of multiple polyols), a catalyst, a surfactant and water; providing a second precursor component including an isocyanate; and providing a plurality of bait material pieces in a bait enclosure. The first and second components are then mixed, which initiates the curing process, and the mixture is poured into the bait enclosure, thereby entering the void space between the bait material pieces and the bait enclosure. As the mixture cures, it expands to fill additional portions of the void space. It is within the purview of a person of ordinary skill in the art to provide a sufficient quantity of ingredients such that, as the mixture cures, it fills substantially all of the void space in the bait enclosure, if desired. In some cases, it may be desirable to include a slight excess of the mixture to ensure that substantially the entire void space is filled with polyurethane foam at the completion of the curing reaction. In an embodiment that utilizes a mold as the bait enclosure, at the completion of the curing reaction, the composite bait material can be removed from the mold for subsequent use. In addition, a composite bait material removed from a mold can optionally be subjected to further processing prior to use, such as, for example, by roughening the surface of the composite bait material to improve termite penetration. If curing is accomplished in a bait container, the bait material within the bait container is ready for use as a termite control device upon completion of curing, optionally with surface roughening at exposed surfaces of the composite bait material. 
     In one embodiment, polyurethane foam matrix  3  of composite bait material  1  comprises a rigid, closed-cell polyurethane foam. In other alternative embodiments, polyurethane foam matrix  3  of composite bait material  1  is a flexible closed-cell polyurethane foam, a rigid open-cell polyurethane foam or a flexible open-cell polyurethane foam. The foam matrices having these different physical properties can be made by adjusting the ingredients included in the mixture of polyurethane foam precursors, and is within the purview of a person of ordinary skill in the art. It is understood that a wide variety of polyurethane foam precursors and also a wide variety of process parameters (such as temperature and pressure) can be used to provide composite bait materials having various physical characteristics. It is within the ability of a skilled artisan, armed with the description of the present application, to select, without undue experimentation, advantageous combinations of polyurethane foam precursors and parameters to provide articles having differing physical features, such as, for example, different densities and rigidities. 
     When a stand-alone bait material is made using a mold, food material pieces  2  can be held away from the walls of the mold cavity to ensure that a continuous polyurethane foam barrier is formed around food material pieces  2 . This can be achieved, for example, by positioning one or more structures in the mold prior to introduction of food material pieces into the mold to hold the food material pieces away from the walls of the mold cavity, thereby providing a space between the food material and the walls of the mold cavity. With the food material spaced apart from the walls of the mold cavity in this way, expansion and curing of the polyurethane foam in the mold provides a substantially continuous layer of polyurethane foam that surrounds or substantially surrounds all of the food material in the mold. This can be achieved in a variety of ways within the purview of a person of ordinary skill in the art. As one example, a preformed hollow polyurethane tube having outer dimensions generally corresponding to the inner dimensions of the mold cavity can be placed in the mold before introducing the food material pieces into the mold, thereby spacing the food material pieces away from the walls of the mold cavity. In this approach, the preformed polyurethane tube will become integrated into the composite bait material and will become an integral part of matrix  3 . In another embodiment, such hollow polyurethane tube can itself operate as a mold that becomes part of the composite bait material upon curing of the polyurethane foam precursors. As another example, the food material pieces can be placed in a separate container configured to be placed in the mold such that it is spaced apart from the walls of the mold cavity. The container can itself be composed of a cellulosic food material, or alternatively can be composed of a non-food material. If the container is composed of non-food material, it can have a screen-like, net-like or scaffold-like configuration, thereby providing openings suitable for passage of termites. 
     In another embodiment, composite bait material  1  includes a termite feeding enhancer (hereafter “enhancer”) integrally entrained in the polyurethane foam. The enhancer comprises a material that is dispersible or soluble in the mixture of polyurethane foam precursors, and is thereby capable of becoming entrained in polyurethane foam matrix  3  as it cures to become an integral component of the polyurethane foam. In one embodiment, the enhancer comprises a dispersible or soluble food material (hereafter “food material enhancer”), such as, for example, a particulate cellulosic material or a sugar. In another embodiment, the enhancer comprises a non-food attractant, such as, for example, a natural or synthetic chemical or biochemical compound or mixture of compounds that is effective to enhance termite feeding or tunneling activity in a polyurethane foam comprising same (hereafter “chemical enhancer”). The term “sugar” is used herein to refer to a monosaccharide, disaccharide, polysaccharide or other carbohydrate substance that is an acceptable food for termites. The presence of a food material enhancer increases the palatability of the polyurethane foam to the termites, thereby increasing the attractiveness of the bait material to the termites. 
     To make a bait material including an enhancer, an enhancer is included in the uncured mixture of polyurethane foam precursors before the mixture is introduced into the void space in the bait enclosure and allowed to cure. For example, in one embodiment, alpha-cellulose powder is mixed into the polyol precursor component prior to mixing it with the isocyanate component to initiate the curing reaction. A bait material made in this manner includes the enhancer entrained in the polyurethane foam matrix, thereby enhancing the attractiveness and/or palatability of the polyurethane foam matrix. In one embodiment, a particulate cellulosic material is included in an amount that will produce a polyurethane foam having up to about 95 parts cellulose to 100 parts polyurethane, by weight. In another embodiment, a particulate cellulosic material is included in an amount that will produce a polyurethane foam having from about 1 to about 75 parts cellulose to 100 parts polyurethane, by weight. In another embodiment, a particulate cellulosic material is included in an amount that will produce a polyurethane foam having from about 1 to about 45 parts cellulose to 100 parts polyurethane, by weight. In yet another embodiment, a particulate cellulosic material is included in an amount that will produce a polyurethane foam having from about 5 to about 30 parts cellulose to 100 parts polyurethane, by weight. In still another embodiment, a particulate cellulosic material is included in an amount that will produce a polyurethane foam having from about 5 to about 25 parts cellulose to 100 parts polyurethane, by weight. In still yet another embodiment, a particulate cellulosic material is included in an amount that will produce a polyurethane foam having from about 5 to about 20 parts cellulose to 100 parts polyurethane, by weight. The above proportions are directed to the amount of particulate cellulose material entrained in the polyurethane foam, and do not include the amount of cellulose that may additionally be included in cellulosic food material pieces that may also be encapsulated by the foam. As will be appreciated by a person skilled in the art in view of the present disclosure, the present application encompasses embodiments in which the composite bait material includes polyurethane foam encapsulating cellulosic food material pieces and also includes an enhancer is entrained in the polyurethane foam, embodiments in which cellulosic food material pieces are absent and the composite bait material includes an enhancer is entrained in the polyurethane foam, and embodiments in which the composite bait material includes polyurethane foam encapsulating cellulosic food material pieces and the enhancer is absent from the polyurethane foam. 
     In yet another manner of making a composite bait material, a food material enhancer, such as, for example, a sugar or a particulate cellulosic material, or a chemical enhancer is mixed into an uncured mixture of polyurethane foam precursors, and the mixture is introduced into an empty container, such as, for example, an empty bait container or an empty mold, for curing. In this embodiment, the food material enhancer entrained in the polyurethane foam is utilized as a food source for the termites, and cellulosic food material pieces  2  of composite bait material  1  can be omitted. In this embodiment, additional enhancers can optionally be included in addition to the food material enhancer. In yet another embodiment, an enhancer can be applied to cellulosic food material pieces  2  prior to forming the foam matrix. For example, pieces  2  can be soaked in or coated with a chemical enhancer or a solution of food material enhancer, such as, for example, a sugar solution, prior to formation of matrix  3 . 
     The present application is not intended to be limited to the manufacture of bait material products having a specific shape. Rather, a wide variety of shapes are envisioned. Articles made in accordance with the application can be formed into a wide variety of shapes and sizes by mold design, by post-curing processing or by a combination thereof. In one embodiment, the composite bait material is contained within a bait tube as described further hereinbelow. 
     Another aspect of the application is a moisture-resistant composite bait material that includes a cellulosic food material member that is palatable to termites, encapsulated within a termite-edible or termite-displaceable polyurethane foam coating. The foam coating provides a water resistant barrier between the cellulosic food material member and its environment. With reference to the embodiment depicted in  FIG. 2 , composite bait material  4  includes cellulosic food material member  5  and polyurethane foam coating  6 . Cellulosic food material member  5  can be composed of, for example and without limitation, an extruded cellulosic food material, a piece of wood, a termite-edible or termite-displaceable material for an ESP monitor or a termite-edible or termite-displaceable material for a HALO™ monitoring device. For example, member  5  can comprise a material including a thermoplastic polymer, such as, for example, a material made as described in the commonly-owned U.S. Patent Application Publication No. 2008/0187565. For example, cellulosic food material member  5  can be made by molding, extruding or otherwise processing a mixture of a thermoplastic material and a pest food material, with or without a pesticide included therein. Polyurethane foam coating  6  can also include an enhancer entrained therein, as described above in connection with polyurethane matrix  3 . 
     Coating  6  can be applied to member  5 , for example, by providing a first precursor component that includes a polyol (or optionally a mixture of multiple polyols), a catalyst, and optionally additional ingredients, such as, for example, a surfactant and water; providing a second precursor component including an isocyanate; and providing a cellulosic food material member. The first and second components are then mixed, which initiates the curing process, and the mixture is coated on the food material member to cure thereon. As the mixture cures, it produces a polyurethane coating over the surface of the food material member. The mixture can be coated on food material members in a variety of ways that would occur to a person of ordinary skill in the art. For example, in one manner of coating food material member  5 , member  5  is dipped in the mixture, and then, after, withdrawing member  5  from the mixture, the mixture remaining on the surface of member  5  is allowed to cure. If desired, this process can be repeated one or more times to apply polyurethane foam coating  6  to member  5  in layers until a desired thickness is achieved. In another manner of applying coating  6  to member  5 , the member is placed into a mold or other container, such as, for example, a polyethylene pipe having internal dimensions corresponding to the desired final dimensions of the composite bait material, which are greater than the dimensions of the extruded food material member. With the food material member positioned such that it does not contact the walls of the cavity defined by the mold or other container, the mixture is poured into the container, thereby entering the void space between the food material member and the walls of the cavity. As the mixture cures, it produces a polyurethane coating over the surface of the food material member, the coating having external dimensions corresponding to the internal dimensions of the cavity. 
     As stated above, bait materials described herein can be made without pesticides, or can optionally include one or more pesticides. In the manufacture of composite bait materials that include pesticides, the pesticide can be entrained in the food material or in the uncured mixture of polyurethane foam precursors for subsequent incorporation into the polyurethane foam. The term “food material” is used herein collectively to refer to cellulosic food material pieces, a food material enhancer, such as, for example, particulate cellulosic or sugar material, or a cellulosic food material member, depending upon the particular configuration of the composite bait material. For example, in one manner of incorporating a pesticide into a bait material, a particulate cellulosic material, such as, for example, purified alpha cellulose, is first pre-loaded with a pesticide. In one manner of pre-loading, the pesticide is sprayed directly on cellulose particles. The pesticide-treated cellulose particles can be incorporated directly into a mixture of polyurethane foam precursors as a food enhancer, as described above. Then, upon curing of the mixture, the pesticide-loaded particles become entrained in a polyurethane foam matrix. Alternatively, the pesticide-treated cellulose particles can be mixed with other materials for extrusion to form an extruded, pesticide-containing food material member. As yet another alternative, pesticide-treated cellulose particles can be compacted and broken into prills, which include the cellulose food material and the pesticide therein, and which can be used as food material pieces. In another manner of pre-loading the food material with a pesticide, pre-formed prills of cellulose (which are available commercially, and can be obtained from International Fiber) are sprayed with the pesticide to provide a pesticide-loaded cellulose material. The cellulose/pesticide prills can then be placed into a bait enclosure as described above for subsequent introduction of a mixture of polyurethane foam material precursors. Pesticides can also be sprayed onto other types of cellulosic food materials, such as, for example, wood blocks, cardboard, sawdust and the like, which can then be included in an uncured mixture of polyurethane foam precursors (in the case of sawdust or other particulate material) or placed into a bait enclosure for subsequent introduction of a mixture of polyurethane foam material precursors. 
     A pesticide alternatively can be incorporated into a composite bait material by mixing the pesticide directly into the mixture of polyurethane foam precursors. Upon curing of the mixture, a polyurethane foam having the pesticide entrained therein is formed. As yet another example, which can be employed in the manufacture of a bait material having an open-cell configuration, the pesticide can be incorporated into the bait material after the polyurethane foam is cured by soaking the bait material in a pesticide-containing fluid. Upon soaking, the pesticide will enter the pores of the polyurethane foam matrix, thereby becoming entrained therein. Moreover, if the bait material is allowed to soak for a sufficient period of time, the pesticide can move through the network of passages formed in the open-cell foam and come into contact with the cellulosic food material entrained in the polyurethane foam matrix, and become entrained in the food material also. 
     The pesticide is one that is effective to kill pests that ingest or contact the pesticide. Some of the pesticides that can be employed in a composite material as disclosed herein include, but are not limited to the following: 
     1,2 dichloropropane, 1,3 dichloropropene, 
     abamectin, acephate, acequinocyl, acetamiprid, acethion, acetoprole, acrinathrin, acrylonitrile, alanycarb, aldicarb, aldoxycarb, aldrin, allethrin, allosamidin, allyxycarb, alpha cypermethrin, alpha ecdysone, amidithion, amidoflumet, aminocarb, amiton, amitraz, anabasine, arsenous oxide, athidathion, azadirachtin, azamethiphos, azinphos ethyl, azinphos methyl, azobenzene, azocyclotin, azothoate, 
     barium hexafluorosilicate, barthrin, benclothiaz, bendiocarb, benfuracarb, benomyl, benoxafos, bensultap, benzoximate, benzyl benzoate, beta cyfluthrin, beta cypermethrin, bifenazate, bifenthrin, binapacryl, bioallethrin, bioethanomethrin, biopermethrin, bistrifluoron, borax, boric acid, bromfenvinfos, bromo DDT, bromocyclen, bromophos, bromophos ethyl, bromopropylate, bufencarb, buprofezin, butacarb, butathiofos, butocarboxim, butonate, butoxycarboxim, 
     cadusafos, calcium arsenate, calcium polysulfide, camphechlor, carbanolate, carbaryl, carbofuran, carbon disulfide, carbon tetrachloride, carbophenothion, carbosulfan, cartap, chinomethionat, chlorantraniliprole, chlorbenside, chlorbicyclen, chlordane, chlordecone, chlordimeform, chlorethoxyfos, chlorfenapyr, chlorfenethol, chlorfenson, chlorfensulphide, chlorfenvinphos, chlorfluazuron, chlormephos, chlorobenzilate, chloroform, chloromebuform, chloromethiuron, chloropicrin, chloropropylate, chlorphoxim, chlorprazophos, chlorpyrifos, chlorpyrifos methyl, chlorthiophos, chromafenozide, cinerin I, cinerin II, cismethrin, cloethocarb, clofentezine, closantel, clothianidin, copper acetoarsenite, copper arsenate, copper naphthenate, copper oleate, coumaphos, coumithoate, crotamiton, crotoxyphos, cruentaren A &amp;B, crufomate, cryolite, cyanofenphos, cyanophos, cyanthoate, cyclethrin, cycloprothrin, cyenopyrafen, cyflumetofen, cyfluthrin, cyhalothrin, cyhexatin, cypermethrin, cyphenothrin, cyromazine, cythioate, 
     d-limonene, dazomet, DBCP, DCIP, DDT, decarbofuran, deltamethrin, demephion, demephion O, demephion S, demeton, demeton methyl, demeton O, demeton O methyl, demeton S, demeton S methyl, demeton S methylsulphon, diafenthiuron, dialifos, diamidafos, diazinon, dicapthon, dichlofenthion, dichlofluanid, dichlorvos, dicofol, dicresyl, dicrotophos, dicyclanil, dieldrin, dienochlor, diflovidazin, diflubenzuron, dilor, dimefluthrin, dimefox, dimetan, dimethoate, dimethrin, dimethylvinphos, dimetilan, dinex, dinobuton, dinocap, dinocap 4, dinocap 6, dinocton, dinopenton, dinoprop, dinosam, dinosulfon, dinotefuran, dinoterbon, diofenolan, dioxabenzofos, dioxacarb, dioxathion, diphenyl sulfone, disulfuram, disulfoton, dithicrofos, DNOC, dofenapyn, doramectin, 
     ecdysterone, emamectin, EMPC, empenthrin, endosulfan, endothion, endrin, EPN, epofenonane, eprinomectin, esfenvalerate, etaphos, ethiofencarb, ethion, ethiprole, ethoate methyl, ethoprophos, ethyl DDD, ethyl formate, ethylene dibromide, ethylene dichloride, ethylene oxide, etofenprox, etoxazole, etrimfos, EXD, 
     famphur, fenamiphos, fenazaflor, fenazaquin, fenbutatin oxide, fenchlorphos, fenethacarb, fenfluthrin, fenitrothion, fenobucarb, fenothiocarb, fenoxacrim, fenoxycarb, fenpirithrin, fenpropathrin, fenpyroximate, fenson, fensulfothion, fenthion, fenthion ethyl, fentrifanil, fenvalerate, fipronil, flonicamid, fluacrypyrim, fluazuron, flubendiamide, flubenzimine, flucofuron, flucycloxuron, flucythrinate, fluenetil, flufenerim, flufenoxuron, flufenprox, flumethrin, fluorbenside, fluvalinate, fonofos, formetanate, formothion, formparanate, fosmethilan, fospirate, fosthiazate, fosthietan, fosthietan, furathiocarb, furethrin, furfural, 
     gamma cyhalothrin, gamma HCH, 
     halfenprox, halofenozide, HCH, HEOD, heptachlor, heptenophos, heterophos, hexaflumuron, hexythiazox, HHDN, hydramethylnon, hydrogen cyanide, hydroprene, hyquincarb, 
     imicyafos, imidacloprid, imiprothrin, indoxacarb, iodomethane, IPSP, isamidofos, isazofos, isobenzan, isocarbophos, isodrin, isofenphos, isoprocarb, isoprothiolane, isothioate, isoxathion, ivermectin 
     jasmolin I, jasmolin II, jodfenphos, juvenile hormone I, juvenile hormone II, juvenile hormone III, 
     kelevan, kinoprene, 
     lambda cyhalothrin, lead arsenate, lepimectin, leptophos, lindane, lirimfos, lufenuron, lythidathion, 
     malathion, malonoben, mazidox, mecarbam, mecarphon, menazon, mephosfolan, mercurous chloride, mesulfen, mesulfenfos, metaflumizone, metam, methacrifos, methamidophos, methidathion, methiocarb, methocrotophos, methomyl, methoprene, methoxychlor, methoxyfenozide, methyl bromide, methyl isothiocyanate, methylchloroform, methylene chloride, metofluthrin, metolcarb, metoxadiazone, mevinphos, mexacarbate, milbemectin, milbemycin oxime, mipafox, mirex, MNAF, monocrotophos, morphothion, moxidectin, 
     naftalofos, naled, naphthalene, nicotine, nifluridide, nikkomycins, nitenpyram, nithiazine, nitrilacarb, novaluron, noviflumuron, 
     omethoate, oxamyl, oxydemeton methyl, oxydeprofos, oxydisulfoton, 
     paradichlorobenzene, parathion, parathion methyl, penfluoron, pentachlorophenol, permethrin, phenkapton, phenothrin, phenthoate, phorate, phosalone, phosfolan, phosmet, phosnichlor, phosphamidon, phosphine, phosphocarb, phoxim, phoxim methyl, pirimetaphos, pirimicarb, pirimiphos ethyl, pirimiphos methyl, potassium arsenite, potassium thiocyanate, pp′ DDT, prallethrin, precocene I, precocene II, precocene III, primidophos, proclonol, profenofos, profluthrin, promacyl, promecarb, propaphos, propargite, propetamphos, propoxur, prothidathion, prothiofos, prothoate, protrifenbute, pyraclofos, pyrafluprole, pyrazophos, pyresmethrin, pyrethrin I, pyrethrin II, pyridaben, pyridalyl, pyridaphenthion, pyrifluquinazon, pyrimidifen, pyrimitate, pyriprole, pyriproxyfen, quassia, quinalphos, quinalphos, quinalphos methyl, quinothion, quantifies, 
     rafoxanide, resmethrin, rotenone, ryania, 
     sabadilla, schradan, selamectin, silafluofen, sodium arsenite, sodium fluoride, sodium hexafluorosilicate, sodium thiocyanate, sophamide, spinetoram, spinosad, spirodiclofen, spiromesifen, spirotetramat, sulcofuron, sulfuram, sulfluramid, sulfotep, sulfur, sulfuryl fluoride, sulprofos, 
     tau fluvalinate, tazimcarb, TDE, tebufenozide, tebufenpyrad, tebupirimfos, teflubenzuron, tefluthrin, temephos, TEPP, terallethrin, terbufos, tetrachloroethane, tetrachlorvinphos, tetradifon, tetramethrin, tetranactin, tetrasul, theta cypermethrin, thiacloprid, thiamethoxam, thicrofos, thiocarboxime, thiocyclam, thiodicarb, thiofanox, thiometon, thionazin, thioquinox, thiosultap, thuringiensin, tolfenpyrad, tralomethrin, transfluthrin, transpermethrin, triarathene, triazamate, triazophos, trichlorfon, trichlormetaphos 3, trichloronat, trifenofos, triflumuron, trimethacarb, triprene, 
     vamidothion, vamidothion, vaniliprole, vaniliprole, 
     XMC, xylylcarb, 
     zeta cypermethrin and zolaprofos. 
     Additionally, any combination of the above pesticides can be used. 
     For more information consult “Compendium of Pesticide Common Names” located at http://www.alanwood.net/pesticides/index.html as of the filing date of this document. Also consult “The Pesticide Manual” 14th Edition, edited by C D S Tomlin, copyright 2006 by British Crop Production Council. 
     In one embodiment, the pesticide is one that has an immediate effect upon ingestion by or contact with a pest (referred to herein as an “immediate action” pesticide or a “fast acting” pesticide). For example, insecticides that have immediate killing action upon ingestion by termites include chlorpyrifos, spinosad, imidacloprid and fipronil, each of which is well known and available commercially. As used herein, the terms “immediate action” and “fast acting” are intended to mean that the pesticide typically operates to kill an individual pest before the pest returns to its colony. In another embodiment, the pesticide is one that exhibits a delayed effect upon ingestion by or contact with a pest (referred to herein as a “delayed action” pesticide). For example, insecticides that have delayed killing activity upon ingestion by or contact with termites include hexaflumuron and noviflumuron, each of which is well known and available commercially. As used herein, the term “delayed action” is intended to mean that the pesticide typically does not operate to kill an individual pest until after the pest has returned to its colony. In another embodiment, the pesticide is selected from the group consisting of lufenuron, diflubenzuron, flufenoxuron and hydramethylnon. 
     In addition to the polyurethane foam, the food material and optionally a pesticide, other ingredients can optionally be included in the composite bait material. For example, some ingredients can be included to increase the stability or shelf life of the pesticide included in the composite. Other ingredients can be selected to improve the compatability of the substances present in the bait material, or to provide an advantageous effect after the bait material is formed. Still other ingredients can be selected, for example, as attractants to enhance the attraction of pests to the baits or to stimulate feeding. The composite materials disclosed herein can also include or be used with herbicides and fungicides, both for reasons of economy and synergy. The composite bait materials disclosed herein can also include or be used with antimicrobials, bactericides, defoliants, safeners, synergists, algaecides, attractants, desiccants, pheromones, repellants, animal dips, avicides, disinfectants, semiochemicals, and molluscicides (these categories not necessarily mutually exclusive) for reasons of economy, and synergy. 
     A composite bait material as provided herein can be used as a stand-alone bait for attracting and terminating pests as a single-step pesticide delivery tool without the need for monitoring by pest control professionals to determine whether such pests are present in a given area. Alternatively, it can be used as a bait for a pest control device or system that employs monitoring steps for determining the presence or absence of wood destroying pests. For example, it can be used as a replacement monitor or a pesticide-delivery bait in an already existing termite bait station such as, for example, a SENTRICON TERMITE COLONY ELIMINATION SYSTEM® bait station. Whether the bait material is used as a stand-alone bait or as a replacement monitor or bait in an already existing termite bait station, the foam operates to provide a physical barrier between the cellulosic food material and its environment. In some embodiments that include open-cell polyurethane foam, the foam operates to hold moisture in contact with the bait material. In other embodiments, including those that include closed-cell polyurethane foam, and some open-cell embodiments, when the device is exposed to environmental moisture, the foam is operable to reduce or prevent exposure of the bait to the environmental moisture. 
     Thus, in another aspect, the present application provides a pest control device that includes a composite bait material including a cellulosic food material and a polyurethane foam. In one form, a moisture-resistant termite control device includes a bait container that defines one or more slots, holes and/or apertures for access by termites and that includes a chamber for containing the composite bait material. The bait container also includes an upper end portion defining an upper opening into the chamber, a closure to selectively access and close the upper opening, a side wall and a lower end portion defining a bottom terminus of the bait container. The container may be placed in the cavity of an in-ground housing previously installed in the ground or may be used without such a housing. In another embodiment, the device includes a container, such as, for example, a bait tube, that includes polyurethane foam but does not include a cellulosic food material. Alternatively or additionally, the container may include a sensor to detect pest presence. The sensor can be embedded in polyurethane foam without a cellulosic food material, or can be embedded in a composite bait material that includes a cellulosic food material and a polyurethane foam. The pest control system  20  of  FIGS. 3-11  provides a further example of such an implementation. 
       FIG. 3  illustrates pest control system  20 . System  20  is arranged to protect building  22  from damage due to pests, such as subterranean termites. System  20  includes a number of pest control devices  110  positioned about building  22 . In  FIG. 3 , only a few of devices  110  are specifically designated by reference numerals to preserve clarity. System  20  also includes a portable interrogator  30  to gather information about devices  110 . Data gathered from devices  110  with interrogator  30  is collected in Data Collection Unit (DCU)  40  through communication interface  41 . In other implementations, DCU  40  may not be present or only optionally utilized, instead using interrogator  30  as the terminal data gathering equipment. 
     Referring additionally to  FIG. 4 , certain aspects of the operation of system  20  are illustrated. In  FIG. 4 , a pest control service provider P is shown operating interrogator  30  to interrogate pest control devices  110  located at least partially below ground G using a wireless communication technique that does not require electrical contact between interrogator  30  and device  110  as further explained hereinafter. In this example, interrogator  30  is shown in a hand-held form convenient for sweeping over ground G to establish wireless communication with installed devices  110 . As an alternative or in addition to this contactless technique, interrogator  30  may make electrical and/or mechanical contact with each device  110  to gather data. In lieu of or along with interrogator  30 , information about each pest control device  110  can be reported in a different manner, such as with a visual and/or aural indicator fixed to device  110  in still other embodiments. 
       FIGS. 5-11  illustrate various features of pest control device  110 . To detect pests, and optionally apply a pesticide, pest control device  110  is internally configured with pest monitoring assembly  112  structured for assembly in a bait container as further described in connection with  FIGS. 8-11 . Referring more specifically to  FIGS. 5 and 6 , pest monitoring assembly  112  is illustrated in part along centerline assembly axis A. Axis A coincides with the view planes of both  FIGS. 5 and 6 ; where the view plane of  FIG. 6  is perpendicular to the view plane of  FIG. 5 . 
     Pest monitoring assembly  112  includes sensor subassembly  114  below communication circuit subassembly  116  along axis A. Sensor subassembly  114  includes sensor  150 . Sensor  150  is structured for contact with bait as more fully described hereinafter in connection with  FIGS. 11 and 12 ; however, certain details of sensor  150  are described first as follows. Sensor  150  is generally elongated and has end portion  152   a  opposite end portion  152   b  as shown in  FIGS. 5 and 6 , for example. A middle portion of sensor  150  is represented by a pair of adjacent break lines separating portions  152   a  and  152   b  in  FIGS. 5 and 6 . Sensor  150  includes sensing substrate  151 . Substrate  151  carries conductor  153  that is arranged to provide sensing element  153   a  in the form of an electrically conductive loop or pathway  154  shown in the broken view of  FIG. 6 . Along the middle sensor portion represented by the break lines of  FIG. 6 , the two segments of pathway  154  continue along a generally straight, parallel route (not shown), and correspondingly end at contact pads  32  at along an edge of end portion  152   a . While one shape for pathway  154  is depicted in  FIG. 6 , the present application contemplates that alternative shapes can be utilized, it being understood that the ultimate goal is to increase the likelihood of detecting termites that are feeding in the area of element  153   a . An electrically insulating film  34  covers a portion of each of the segments along end portion  152   a . The film-covered segment portions are shown in phantom. Aperture  36  is formed through substrate  151  between the segments covered by film  34  that may be used for manufacturing and/or handling. At end portion  152   b , the segments join each other to form pathway  154 , completing the electrically conductive loop. 
     Substrate  151  and/or conductor  153  are/is comprised of one or more materials susceptible to consumption or displacement by the pests being monitored with pest monitoring assembly  112 . These materials can be a food substance, a nonfood substance, or a combination of both for the one or more pest species of interest. Indeed, it has been found that materials composed of nonfood substances will be readily displaced during the consumption of adjacent edible materials by termites. As substrate  151  or conductor  153  are consumed or displaced, pathway  154  is eventually altered. This alteration can be utilized to indicate the presence of pests by monitoring one or more corresponding electrical properties of pathway  154  as will be more fully described hereinafter. Alternatively, substrate  151  and/or conductor  153  can be oriented with respect to bait members  132  so that a certain degree of consumption or displacement of bait members  132  exerts a mechanical force sufficient to alter the electrical conductivity of pathway  154  in a detectable manner. For this alternative, substrate  151  and/or conductor  153  need not be directly consumed or displaced by the pest of interest. 
     In one embodiment directed to subterranean termites, substrate  151  is formed from a cellulose material that is consumed, displaced, or otherwise removed by the termites. One specific example includes a paper coated with a polymeric material, such as polyethylene. In other embodiments, substrate  151  may be composed of different materials that target termites and/or other pests of interest. 
     In one form, conductor  153  is provided by a carbon-based conductive material, such as a carbon-containing ink compound. One source of such ink is the Acheson Colloids Company with a business address of 1600 Washington Ave., Port Huron, Mich. 48060. Carbon-containing conductive ink comprising conductor  153  can be deposited on substrate  151  using a silk screening, pad printing, or ink jet dispensing technique; or such other technique as would occur to those skilled in the art. Compared to commonly selected metallic conductors, a carbon-based conductor can have a higher electrical resistivity. Preferably, the volume resistivity of the carbon-containing ink compound is greater than or equal to about 0.001 ohm-cm (ohm-centimeter). In a more preferred embodiment, the volume resistivity of conductor  153  comprised of a carbon-containing material is greater than or equal to 0.1 ohm-cm. In a still more preferred embodiment, the volume resistivity of conductor  153  comprised of a carbon-containing material is greater than or equal to about 10 ohms-cm. In yet other embodiments, conductor  153  can have a different composition or volume resistivity as would occur to those skilled in the art. One example of an ink that is suitable for use as described above is Electrodag 423SS, which is commercially available from Acheson Colloids Company. 
     Pest monitoring assembly  112  further includes circuit subassembly  116  removably connectable to sensor subassembly  114 . Circuit subassembly  116  is arranged to detect and communicate pest activity as indicated by a change in one or more electrical properties of pathway  154  of sensor subassembly  114 . Circuit subassembly  116  includes circuit enclosure  118  for communication circuitry  160  and a pair of connection members  140  for detachably coupling communication circuitry  160  to sensor  150  of sensor subassembly  114 . Enclosure  118  includes cover piece  120 , o-ring  124 , and base  130 , that each have a generally circular outer perimeter about axis A. Enclosure  118  is shown more fully assembled in  FIG. 6  than in  FIG. 5 . Cover piece  120  defines cavity  122 . Base  130  defines channel  131  (shown in phantom) sized to receive o-ring  124  (see  FIG. 6 ). As an alternative or addition to the O-ring  124 , a heat seal may be used. 
     Communication circuitry  160  is positioned between cover piece  120  and base  130 . Communication circuitry  160  includes coil antenna  162  and printed wiring board  164  carrying circuit components  166 . Referring also to  FIG. 7 , a top view is shown of an assembly of base  130 , connection members  140 , and wireless communication circuitry  160 . In  FIG. 7 , axis A is perpendicular to the view plane and is represented by like labeled cross-hairs. Base  130  includes posts  132  to engage mounting holes through printed wiring board  164 . Base  130  also includes mounts  134  to engage coil antenna  162  and maintain it in fixed relation to base  130  and printed wiring board  164  when assembled together. Base  130  further includes four supports  136  each defining opening  137  therethrough as best illustrated in  FIG. 6 . Base  130  is shaped with a centrally located projection  138  between adjacent pairs of supports  136 . Projection  138  defines recess  139  (shown in phantom in  FIG. 5 ). 
     Referring generally to  FIGS. 5-7 , connection members  140  each include a pair of connection nubs  146 . Each nub  146  has neck portion  147  and head portion  145  that extend from opposing end portions of the respective connection member  140 . For each connection member  140 , projection  148  is positioned between the corresponding pair of nubs  146 . Projection  148  defines recess  149 . Connection members  140  are formed from an electrically conductive, elastomeric material. In one embodiment, each connection member  140  is made from a carbon-containing silicone rubber, such as compound  862  available from TECKNIT USA, having a business address of 135 Bryant Street, Cranford, N.J. 07016. In other embodiments, a different composition can be used. 
     To assemble each connection member  140  to base  130 , the corresponding pair of nubs  146  is inserted through a respective pair of openings  137  of supports  136 , with projection  148  extending into recess  139 . Head portion  145  of each of nubs  146  is sized to be slightly larger than the respective opening  137  through which it is to pass. As a result, during insertion, head portions  145  are elastically deformed until fully passing through the respective opening  137 . Once head portion  145  extends through opening  137 , it returns to its original shape with neck  147  securely engaging the opening margin. As shown in  FIG. 7 , printed wiring board  164  contacts one nub  146  of each connection member  140  after assembly. 
     Once connection members  140  are assembled with base  130 , enclosure  118  is assembled by connecting base  130  to cover piece  120  with o-ring  124  carried in channel  131 . A potting compound may be used inside the resulting structure to reduce moisture intrusion and/or other foreign agents. Further, as previously noted, a heat sealing technique can be used in addition to or in lieu of the o-ring  124 /channel  131  structure. After communication circuit subassembly  116  is assembled, sensor  150  is assembled to subassembly  116  by asserting end portion  152   a  into recess  149  of each connection member  140  carried by base  130 . Connection members  140  are sized to be slightly elastically deformed by the insertion of end portion  152   a  into recess  149 , such that a biasing force is applied by connection members  140  to end portion  152   a  to securely hold sensor  150  in contact therewith. Once end portion  152   a  is inserted into connection members  140 , each pad  32  is electrically contacted by a different one of connection members  140 . In turn, each nub  146  that contacts printed wiring board  164  electrically couples pathway  154  to printed wiring board  164 . 
       FIG. 8  illustrates the resulting assembly of subassembly  114  and  116  as part of an exploded view of a higher assembly stage of pest control device  110 . In  FIG. 8 , pest monitoring assembly  112  is alternatively designated sensing assembly  119 , and collectively represents the assembled form of subassemblies  114  and  116 . Once assembled, sensing assembly  119  is structured to facilitate installation and other handling as a unit.  FIG. 8  also depicts bait container  200  in exploded form, which includes sensing assembly  119  when fully assembled. Bait container  200  also includes a tubular body  202  with an upper end portion  204  opposite a lower end portion  206 . Body  202  is hollow to define interior space  210  to receive bait as more fully described hereinafter. Upper end portion  204  defines upper opening  214  that intersects interior space  210 , lower end portion  206  defines lower opening  216  that also intersects interior space  210 , and body  202  also defines side slots  219  between upper end portion  204  and lower end portion  206  that also intersect interior space  210 . Accordingly, openings  214  and  216  and side slots  219  are in fluid communication with each other. Upper end portion  204  defines exterior helical threading  215  about opening  214 . 
     Sensing assembly  119  is sized and shaped to be received in interior space  210  of container  200  through upper opening  214 . Upper end portion defines a ledge to provide seat  218  upon which enclosure  118  of assembly  119  is structured to rest, suspending substrate  151  below in interior space  210  (See also the views of  FIG. 9  and  FIG. 10 ) when assembly  119  is placed therein. Bait container  200  (and correspondingly pest control device  110 ) further includes closure  90  in the form of a cap  91 . Closure  90  includes interior threading  92  structured to engage exterior threading  215  of upper end portion  204  of body  202 . Cap  91  includes handle  94  structured for grasping by hand or some type of an extraction tool to carry and otherwise manipulate bait container  200  when closure  90  is threadingly attached to container  200  as further described hereinafter. Closure  90  can be selectively rotated relative to upper end portion  204  to be threaded thereto and provide a seal. This state is illustrated in  FIGS. 9 and 10 . Accordingly, after insertion of assembly  119  in interior space  210 , closure  90  can be engaged to upper end portion  204 , and likewise can be removed to access assembly  119  as desired. 
     In addition to containing assembly  119 , interior space  210  also contains composite bait material  227  (shown in  FIGS. 9 and 10 ). Bait material  227  is comprised of a multiple cellulosic food material pieces  229  embedded in polyurethane foam matrix  228 . Composite bait material  227  conforms to the shape of interior space  210  occupying a geometric center thereof and spanning across its longitudinal centerline A. Nonetheless, in other embodiments, bait material  227  may be differently composed to target to a different pest type, may include more or fewer cellulosic food material pieces, may include a single food material piece such as a wood or synthetically formed cellulose block, may include an attractant with or without pesticide, and/or may be otherwise differently constituted. 
     To assemble bait container  200 , sensing assembly  119  is placed in interior space  210  of body  202  through proximal end portion  204  to engage upper seat  218 . After placement of sensing assembly  119  in body  202 , closure  90  is threaded on proximal end portion  204  to close opening  214 . Container  200  is inverted to load cellulosic food material pieces  229  through opening  216  to at least partially fill interior space  210 . In one form, cellulosic food material pieces  229  are distributed along opposite sides of substrate  151 . The body  202  may include one or more interior slots and/or guide flanges (not shown) to assist with maintaining substrate  151  in a desired position as food material pieces  229  are distributed thereabout. After loading cellulosic food material pieces  229 , a mixture of uncured polyurethane foam precursors is then introduced into interior space  210  and allowed to flow into the void space in interior space  210  created by food material pieces  229  and body  202 . The uncured polyurethane precursors can be introduced into interior space  210  by pouring through opening  216  in bait container body  202 , as described above in connection with the manufacture of composite bait material  1 . Alternative, a mixture of polyurethane foam precursors can be provided in a delivery system that includes a blowing agent, such as for example, the GREAT STUFF™ polyurethane foam system that is commercially available from The Dow Chemical Company. As the mixture of precursors cures to form polyurethane foam matrix  228 , it expands to fill additional portions of the void space in interior space  210 , and thereby substantially fill the void space. 
     A skilled artisan will appreciate that, when the mixture of polyurethane foam precursors is poured, blown or otherwise introduced into interior space  210 , some or all of the mixture may escape interior space  210  through slots  219  unless slots  219  are covered during the time period between the time when the mixture of polyurethane foam precursors is introduced into space  210  and the time when curing of the polyurethane foam is complete. Thus, in one manner of making bait container  200 , slots  219  are covered before the polyurethane foam precursors are introduced into interior space  210 . Slots  219  can be covered, for example, by applying a plastic film, such as, for example, shrink wrap, over the sides of body  202  before introducing the precursors into interior space  210 . In one embodiment, the plastic film is a tape having an adhesive on one side to temporarily attach the tape to container body  202 . After the polyurethane foam has cured, and before bait container  200  is put to use, the plastic film is removed to expose the slots and the polyurethane foam through slots  219 . When an adhesive tape is used to cover slots  219 , removal of the tape can operate to roughen the exposed surface of polyurethane foam  228 , which can increase the acceptance of composite bait material  228  to termites in the field. In one embodiment, body  202  also defines a small vent hole (not shown) to allow air to escape interior space  210  as the polyurethane foam cures, thereby equilibrating pressure in interior space  210  as the polyurethane foam cures. Alternatively, opening  216  can operate as a vent. 
     So assembled, bait container  200  includes body  202 , sensing assembly  119 , closure  90 , and composite bait material  227 ; and collectively has upper end portion  200   a  opposite lower end portion  200   b . Upper end portion  200   a  defines top terminus  202   a  of container  200  and lower end portion  200   b  defines bottom terminus  202   b  of container  200 . Body  202  is generally annular/cylindrical; however, in other embodiments the shape of body  202  and one or more other components may vary with corresponding adjustments to accommodate assembly, coupling of components to one another, or the like as would occur to those skilled in the art. Body  202  and closure  90  are comprised of a material suitable for placement in the ground that resists removal/damage by pests that are expected to be present and degradation caused by the environment. In one nonlimiting form, the body  202  and closure  90  are made of an organic polymer compound. 
       FIGS. 9 and 10  illustrate housing  170  of pest control device  110 . Housing  170  is arranged for installation in the ground G as shown, for example, in  FIG. 4 . Housing  170  defines a chamber or interior space  172  intersecting access opening  178 . Bait container  200  is sized for insertion into interior space  172  through opening  178  without any portion of container  200  protruding above opening  178 . Housing  170  has an access end portion  171   a  opposite a below-ground end portion  171   b . End portion  171   b  includes tapered end  175  to assist with placement of pest control device  110  in the ground as illustrated in  FIG. 4 . End  175  terminates in an aperture (not shown). In communication with interior space  172  are preferably a number of passages  174  defined by housing  170 . Passages  174  are particularly well-suited for the ingress and egress of termites from interior space  172 . Housing  170  has a number of protruding flanges a few of which are designated by reference numerals  176   a ,  176   b ,  176   c ,  176   d , and  176   e  in  FIG. 9  to assist with positioning of pest control device  110  in the ground. Housing  170  includes removable cap  180  to cover opening  178 . Cap  180  includes downward prongs  184  arranged to engage channels  179  of housing  170 . After cap  180  is fully seated on housing  170 , it can be rotated to engage prongs  184  in a latching position with a bayonet style connection that resists disassembly. Slot  182  can be used to engage cap  180  with a tool such as a top cap wrench, such as a flat-bladed screwdriver, to assist in rotating cap  180 . Housing  170  and cap  180  can be made of a material resistant to deterioration by expected environmental exposure and resistant to alteration by the pests likely to be detected with pest control device  110 . In one form, these components are made from a polymeric resin like polypropylene or CYCOLAC AR polymeric plastic material available from General Electric Plastics (One Plastics Avenue Pittsfield, Mass. 01201). 
     In a typical application directed to termite control, housing  170  is installed in ground with end portion  171   b  penetrating below ground level and end portion  171   a  being positioned approximately at ground level. With cap  180  removed, bait container  200  is inserted into space  172  of housing  170  through opening  178  to rest therein with lower end portion  200   b  entering first to be farther below ground level than upper end portion  200   a . After placement of bait container  200  in housing  170  in-ground, cap  180  engages end portion  171   a  to cover opening  178 . In relation to such operation and handling of housing  170  and container  200 , portions  171   a  and  200   a  are also designated as proximal end portions, and portions  171   b  and  200   b  are also designated as distal end portions. 
     In one procedure implemented with system  20 , a number of pest control devices  110  are installed in a spaced apart relationship relative to an area to be protected. By way of nonlimiting example,  FIG. 3  provides a diagram of one possible distribution of a number of devices  110  arranged about building  22  to be protected. Typically each of devices  110  is at least partly below ground as illustrated in  FIG. 4 . It has been found that once a colony of termites establishes a pathway to a food source, they will tend to return to this food source. Consequently, devices  110  are placed in selected locations to establish such pathways with any termites that might be in the vicinity of the area or structures desired to be protected, such as building  22 . 
     It has been found that baits installed in the ground are susceptible to various modes of degradation—many resulting from exposure to moisture. Typically, bait fouls or degrades/molds when it is saturated with water such as when the installed housing floods. Furthermore, when sensor  150  includes substrate  151  comprised of a moisture-alterable material, such as various types of paper or the like, it can be subject to water damage that results in a false indication of pest presence. By preventing food material pieces  229  and/or sensor  150  from being degraded in such a manner, the longevity and palatability of bait material  227  to targeted pests is enhanced and sensor  150  operation typically is more reliable. With reference to  FIG. 10 , inclusion of polyurethane foam matrix  228  reduces the chances of water reaching food material pieces  229  and sensor  150  by providing a barrier to moisture reaching food material pieces  229  and sensor  150 . However, the composition of polyurethane foam matrix  228  facilitates removal by termites. Accordingly, as termites encounter housing  170 , they pass through slots  219  and polyurethane foam matrix  228  to reach food material pieces  229 . Because polyurethane foam matrix  228  is composed of a termite palatable or termite displaceable material, termites are likely to form passages therethrough to reach food material pieces  229 . As a result, the moisture barrier presented by polyurethane foam seal  250  is breached as termites feed into composite bait material  227 . 
     As termites reach bait  227  and invade chamber  240 , alteration of substrate  151  is likely and eventually pathway  154  is broken, which can be used to signal the presence of termites with communication circuitry  160  of sensing assembly  119 . In the depicted form, circuitry  160  is of a passive type that reports the status of pathway  154  in response to an external wireless signal from interrogator  30 .  FIG. 11  schematically depicts circuitry of interrogator  30  and pest monitoring assembly  112  for a representative pest control device  110 . Monitoring circuitry  169  of  FIG. 8  collectively represents communication circuitry  160  connected to conductor  153  of sensor  150  by connection members  140 . In  FIG. 11 , pathway  154  of monitoring circuitry  169  is represented with a single-pole, single-throw switch corresponding to the capability of sensor  150  to provide a closed or open electrical pathway in accordance with pest activity. Further, communication circuitry  160  includes sensor state detector  163  to provide a two-state status signal when energized; where one state represents an open or high resistance pathway  154  and the other state represents an electrically closed or continuous pathway  154 . Communication circuit  160  also includes identification code  167  to generate a corresponding identification signal for device  110 . Identification code  167  may be in the form of a predetermined multibit binary code or such other form as would occur to those skilled in the art. 
     Communication circuitry  160  is configured as a passive RF transponder that is energized by an external stimulation or excitation signal from interrogator  30  received via coil antenna  162 . Likewise, detector  163  and code  167  of circuitry  160  are powered by this stimulation signal. In response to being energized by a stimulation signal, communication circuitry  160  transmits information to interrogator  30  with coil antenna  162  in a modulated RF format. This wireless transmission corresponds to the termite presence determined with detector  163  and a unique device identifier provided by identification code  167 . In alternate embodiments, power for signaling termite activity can be provided by one or more batteries. 
       FIG. 11  also illustrates communication circuitry  31  of interrogator  30 . Interrogator  30  includes RF excitation circuit  32  to generate RF stimulation signals and RF receiver (RXR) circuit  34  to receive an RF input. Circuits  32  and  34  are each operatively coupled to controller  36 . While interrogator  30  is shown with separate coils for circuits  32  and  34 , the same coil may be used for both in other embodiments. Controller  36  is operatively coupled to Input/Output (I/O) port  37  and memory  38  of interrogator  30 . Interrogator  30  has its own power source (not shown) to energize circuitry  31  that is typically in the form of an electrochemical cell, or battery of such cells (not shown). Controller  36  may be comprised of one or more components. In one example controller  36  is a programmable microprocessor-based type that executes instructions loaded in memory  38 . 
     I/O port  37  is configured to send data from interrogator  30  to data collection unit  40  as shown in  FIG. 3 . Referring back to  FIG. 3 , further aspects of data collection unit  40  are described. Interface  41  of unit  40  is configured for communicating with interrogator  30  via I/O port  37 . Unit  40  also includes processor  42  and memory  44  to store and process information obtained from interrogator  30  about devices  110 . Processor  42  and memory  44  may be variously configured in an analogous manner to that described for controller  36  and memory  38 , respectively. Further, interface  41 , processor  42 , and memory  44  may be integrally provided on the same integrated circuit chip. 
     Accordingly, for the depicted embodiment communication circuitry  160  transmits bait status and identifier information to interrogator  30  when interrogator  30  transmits a stimulation signal to device  110  within range. RF receiver circuit  34  of interrogator  30  receives the information from device  110  and provides appropriate signal conditioning and formatting for manipulation and storage in memory  38  by controller  36 . Data received from device  110  may be transmitted to data collection unit  40  by operatively coupling I/O port  37  to interface  41 . 
     After placement, installed devices  110  are periodically located and data is loaded from each device  110  by interrogation of the respective wireless communication circuit  160  with interrogator  30 . This data corresponds to bait status and identification information. In this manner, pest activity in a given device  110  may readily be detected without the need to extract or open each device  110  for visual inspection. Further, such wireless communication techniques permit the establishment and building of an electronic database that may be downloaded into data collection device  40  for long term storage. 
     If status signal for a given device  110  indicates a broken pathway  154 , the pest control service provider P can determine whether to visually inspect such device by removing cap  180  and closure  90 , otherwise leaving pest control device in situ within the ground. Alternatively or additionally, the service provider could remove assembly  119  through the open proximal end portion  110   a  of device  110 , provide an unaltered substrate  151  to continue monitoring termite activity, or replace container  200  completely. For example, container  200  can be replaced with a pesticide delivery device that includes a pesticide-containing bait, a variety of which are described herein. Such procedures can be repeated for any other devices  110  for which termite activity is detected. After termite activity is detected, periodic replenishment of bait may be performed with or without further monitoring with sensing assembly  119 . 
     The present application also contemplates a wide variety of modifications to device  110  and, in particular, to container  200 . For example, and without limitation, in another embodiment, food material pieces  229  can be omitted, and, in addition to containing sensing assembly  119 , interior space  210  is filled with polyurethane foam, which can optionally include one or more enhancers entrained therein, as described above. A bait container of this embodiment can be assembled in the same manner as described above in connection with bait container  200 , with the exception that no cellulosic food material pieces are loaded into interior space  210  before introducing the mixture of uncured polyurethane foam precursors. In yet another embodiment, sensing assembly  119  can be omitted, in which case interior space  210  is filled with composite bait material  227 . This embodiment can be used, for example, as a monitoring device that can be checked by a service provider for termite activity by visual inspection. Alternatively, if a pesticide is included in composite bait material  227 , this embodiment can be used as a pesticide delivery device. In yet another embodiment, sensing assembly  119  and food material pieces  229  can both be omitted, in which case interior space  210  is filled with polyurethane foam, which can optionally include one or more enhancers entrained therein, as described above. This embodiment can likewise be used, for example, as a monitoring device for visual inspection or as a pesticide delivery device. 
     With reference now to  FIGS. 12-14 , the present application also provides a pest control device that includes a polyurethane foam component positioned at a location separate from cellulosic food material to provide a barrier between the food material and the environment of the device. The polyurethane foam component operates to seal a termite access opening in the device to provide a moisture barrier, thereby reducing bait damage cause by unwanted water intrusion into the device, for example, when the device is installed in the ground. In one embodiment, depicted in  FIGS. 12-14 , pest control device  310  is similar to pest control device  110  in certain respects, and can be substituted for device  110  in system  20  described above, but device  310  includes bait container  400  in place of bait container  200 .  FIG. 12 , in a manner similar to  FIG. 8 , illustrates the resulting assembly of subassembly  114  and  116  as part of an exploded view of a higher assembly stage of pest control device  310 . In  FIG. 12 , like  FIG. 8 , pest monitoring assembly  112  is alternatively designated sensing assembly  119 , and collectively represents the assembled form of subassemblies  114  and  116 .  FIG. 12  also depicts bait container  400  in exploded form, which includes sensing assembly  119  when fully assembled. Bait container  400  also includes a tubular body  402  with an upper end portion  404  opposite a lower end portion  406 . Body  402  is hollow to define interior space  410  to receive bait as more fully described hereinafter. Upper end portion  404  defines upper opening  414  that intersects interior space  410  and lower end portion  406  defines lower opening  416  and optional side openings  419  that also intersect interior space  410 . Accordingly, openings  414 ,  416  and  419  are in fluid communication with each other prior to full assembly of bait container  400 . Upper end portion  404  defines exterior helical threading  415  about opening  414  to receive and engage threading  92  on closure  90 . 
     Sensing assembly  119  is sized and shaped to be received in interior space  410  of container  400  through upper opening  414 . Upper end portion  404  defines a ledge to provide seat  418  upon which enclosure  118  of assembly  119  is structured to rest, suspending substrate  151  below in interior space  410  (See also the views of  FIG. 13  and  FIG. 14 ) when assembly  119  is placed therein. As described hereinabove, closure  90  includes interior threading  92  structured to engage exterior threading  415  of upper end portion  404  of body  402 . Cap  91  includes handle  94  structured for grasping by hand or some type of an extraction tool to carry and otherwise manipulate bait container  400  as further described hereinafter. Closure  90  can be selectively rotated relative to upper end portion  404  to be threaded thereto and provide a water tight seal. This state is illustrated in  FIGS. 13 and 14 . Accordingly, after insertion of assembly  119  in interior space  410 , closure  90  can be engaged to upper end portion  404 , and likewise can be removed to access assembly  119  as desired. 
     Lower end portion  406  defines a ledge to provide seat  420  against which barrier  430  is structured to rest, held in place by polyurethane foam seal  450  that resides in chamber  445  after full assembly of bait container  400  (See also the views of  FIG. 13  and  FIG. 14 ). Barrier member  430  is shaped and sized to fit in interior space  410  through lower opening  416  to engage lower seat  420 . In one form, barrier  430  is a disk comprised of a material that is consumable or displaceable by termites, such as, for example and without limitation, a sheet of cork, paper or wood. Barrier  430  divides interior space  410  of body  402  to define a lower boundary  478  of a bait containing chamber  440  in body  402 , and separating bait containing chamber  440  from chamber  445  that is configured to contain a polyurethane foam seal. Body  400  also defines optional side slots  419  between lower boundary  478  of bait chamber  440  and bottom terminus  402   a  of bait container  400 . 
     In one form targeted to termites, the bait contained in chamber  440  is comprised of multiple pellets  229  that each include a cellulosic food material attractive to termites and optionally also a pesticide. For this form, pellets  229  conform to the shape of chamber  410 , occupying a geometric center thereof and spanning across its longitudinal centerline A. Nonetheless, in other embodiments, the bait may be differently composed to target to a different pest type, may include more or fewer pieces, may be a single piece such as a wood or synthetically formed cellulose block, may include an attractant with or without pesticide, and/or may be otherwise differently constituted. 
     To assemble bait container  400 , sensing assembly  119  is placed in interior space  410  of body  402  through proximal end portion  404  to engage upper seat  418 . After placement of sensing assembly  119  in body  402 , closure  90  is threaded on proximal end portion  404  to close opening  414  with a water tight seal. Container  400  is inverted to load pellets  229  through opening  416  to at least partially fill the portion of interior space  410  that may reach up to lower seat  420 . In one form, pellets  229  are distributed along opposite sides of substrate  151 . Body  402  can optionally include one or more interior slots and/or guide flanges to assist with maintaining substrate  151  in a desired position as pellets  229  are distributed thereabout. Alternatively, sensing assembly  119  can be omitted. After loading pellets, barrier  430  is placed through opening  416  to engage lower seat  420 . With barrier  430  positioned against lower seat  420 , a mixture of uncured polyurethane precursors is then introduced into pocket  445  and allowed to cure to form water resistant polyurethane foam seal  450 . The mixture of uncured polyurethane precursors can be made as described above, and can optionally include an enhancer entrained therein to increase its attractability to termites, if desired. So assembled, bait container  400  includes body  402 , sensing assembly  119 , closure  90 , bait  227 , barrier  430  and polyurethane foam seal  450 ; and collectively has upper end portion  400   a  opposite lower end portion  400   b . Upper end portion  404  defines top terminus  402   a  of container  400  and lower end portion  406  defines bottom terminus  402   b  of container  400 . In addition, if necessary or desired, after the polyurethane foam is cured, it can be trimmed at bottom terminus  402   b  of bait container  400  to a desired shape and/or size. In addition, lower surface of the polyurethane foam optionally can be roughened or otherwise treated to improve attractiveness of the surface to termites. Body  402 , closure  90  and polyurethane foam seal  450  are generally annular/cylindrical; however, in other embodiments shape of one or more of these components may vary with corresponding adjustments to accommodate assembly, coupling of components to one another, or the like as would occur to those skilled in the art. Body  402  and closure  90  are comprised of a material suitable for placement in the ground that resists removal/damage by pests that are expected to be present and degradation caused by the environment. In one nonlimiting form, the body  402  and closure  90  components are made of an organic polymer compound. In an alternate embodiment, barrier  430  may be absent. In this embodiment, pellets  229  contact polyurethane foam seal  450  directly and are held in bait chamber  440  by polyurethane foam seal  450 . 
     Referring to  FIG. 14 , container  400  is structured to reduce the chances of water reaching pellets  229 . As initially installed, barrier  430  and polyurethane foam seal  450  each provide a barrier to moisture reaching lowermost boundary  478  of bait  229 . Accordingly, when closure  90  is engaged to body  402  of container to form a seal therewith, this collective structure of container  400  provides a water-resistant boundary that surrounds bait chamber  440 . However, the composition of barrier  430  and polyurethane foam seal  450  facilitates removal by termites. Accordingly, as termites enter housing  170  through openings  174 , they encounter body  402  of bait container  400 . When the termites encounter side openings  419  or lower opening  416  of bait container  400 , they are able to tunnel through polyurethane foam seal  450  and barrier  430  to reach bait chamber  440 . Because polyurethane foam seal  450  is composed of a termite palatable or termite displaceable material, termites are likely to form passages therethrough to reach barrier  430 . Termites then form passages through barrier  430  to reach bait  227  in bait chamber  440 . As a result of termites tunneling through polyurethane foam seal  450 , the moisture barrier provided by polyurethane foam seal  450  is breached; however, by providing an airtight seal between closure  90  and body  402 , the configuration depicted in  FIGS. 12-14  also operates to provide moisture resistance even after polyurethane foam seal  450  is breached by tunneling termites. Specifically, because the only entry points for termites into bait chamber  440  are below the bait chamber  440 , air that is trapped in interior space  410  of bait container  400  prevents water from entering bait chamber  440  under flooding conditions, even after termites have tunneled through polyurethane foam seal  450  and barrier  430 . For example, if water level in the ground extends higher than the highest external entry point of termites to bait chamber  440  (in this embodiment, the uppermost of slots  419 ), bait container  400  traps air to prevent water from rising inside body  402  to a degree that it will enter into bait chamber  440  given the airtight boundary provided by body  402  down to this external point of entry. While water may pass partially into polyurethane foam seal  450 , air pressure in bait chamber  440  resists passage of water through seal  450  and into bait chamber  440 . In this embodiment, the uppermost of side openings  419  is spaced apart from lower boundary  478  of bait chamber by distance H to provide adequate separation between bait chamber  440  and uppermost side opening  419  to reduce the chances of water reaching bait chamber  440  positioned above the highest side opening  419  under a desired range of environmental conditions. In one preferred form, distance H is about 1 centimeter (cm). In a more preferred form, distance H is about 2.5 cm (1 inch). In another embodiment, side openings  419  are absent and with the only opening into chamber  445  being at lower end  406 , the entire height of chamber  445  can operate to separate bait chamber  440  from water after polyurethane foam seal  450  is breached. 
     In an alternate manner of making bait container  400 , polyurethane foam seal  450  is made as a separate component having a desired shape and size, such as, for example, by forming polyurethane foam seal  450  to shape in a mold or by cutting polyurethane foam seal  450  from a larger polyurethane foam workpiece, and then inserting polyurethane foam seal  450  into chamber  445  through lower end  406 . In this embodiment, barrier  430  can be included or omitted. 
     In an alternative embodiment, barrier  430  can be held in place by fitting  452  depicted in  FIGS. 15 and 16 . Fitting  452  has a cylindrical form that includes sidewalls  460  upper wall  456  (also referred to as “partition  456 ”), and defines a chamber  462  therein. Partition  456  defines a number of openings  458  therethrough. Partition  456  can be an integral portion of fitting  452 , or can be a separate part that is attached to sidewalls  460 . For example, partition  456  can be in the form of a mesh screen attached to sidewalls  460 . In one embodiment, partition  456  is formed from a 7 Mesh plastic canvas available from Uniek, Inc. of Waunakee, Wis. and attached to sidewalls  460  with an adhesive. In an embodiment that includes fitting  452 , lower end portion  406  of body  402  of bait container  400  defines interior helical threading (not shown) about opening  416 , and fitting  452  includes exterior threading  464  to engage interior threading (not shown) of lower end portion  406 . When threaded through opening  416 , fitting  452  holds barrier  430  in place. With barrier  430  and fitting  452  in place, polyurethane foam can be positioned in chamber  462  of fitting  452  to provide a water resistant seal for lower end portion  406 . For the sake of clarity, fitting  452  is omitted from  FIGS. 12, 13 and 14 ; however, it is to be understood that fitting  452  can optionally be included in bait container  400  as described above. 
     To make a bait container  400  that includes fitting  452 , bait  229  is loaded into bait chamber  440  through lower opening  416 , barrier  430  is placed through opening  416  to engage lower seat  420 , and fitting  452  is then threaded into opening  406  to capture barrier  430 . Polyurethane foam seal  450  is then positioned in chamber  462  of fitting  452  as described herein, i.e., by allowing the polyurethane foam seal  450  to cure in chamber  462  or by inserting a pre-made polyurethane foam seal  450  in chamber  462 . So assembled, bait container  400  includes body  402 , closure  90 , barrier  430 , fitting  452  and polyurethane foam seal  450 . 
     In use of an embodiment that includes fitting  452 , as barrier  430  is removed and dispersed by termites, it should be appreciated that partition  456  of fitting  452  is structured to define lowermost boundary  478   b  of bait  229  in bait chamber  440 . As a part of fitting  452 , partition  456  is comprised of a material not readily removed or altered by termites. Thus, while some smaller portions of bait  229  might drop through openings  458 , the larger pieces of bait  227  are maintained by partition  456  in an upwardly offset position within body  402  of container  400  relative to terminus  402   b.    
     A pest control device that omits sensing assembly  119  can be made in a manner similar to that described above, i.e., by affixing closure  90  to upper portion  404  of body  402 , introducing bait material through lower opening  416 , placing barrier  430  against lower seat  420 , and then introducing a mixture of polyurethane foam precursors into chamber  445  for curing. Alternatively, in an embodiment that omits sensing assembly  119 , it is possible to introduce a bait material into space  410  through upper opening  414 . Such an embodiment can be made by first forming polyurethane foam seal in chamber  445  and subsequently introducing the bait material into chamber  410  through upper opening  414 , followed by affixing closure  90  to upper portion  404  of body  402 . In this embodiment, barrier  430  can be included or omitted. If barrier  430  is included, the polyurethane foam seal can be made in the same manner described above, that is, by inverting tube  402 , positioning barrier  430  against lower seat  420 , and pouring a mixture of polyurethane foam precursors into chamber  445  for curing. Alternatively, polyurethane foam seal can be made by introducing a mixture of polyurethane foam precursors into chamber  445  through upper end opening  414 . For example, lower opening  416  can first be blocked by placing a temporary closure over opening  416 , such as, for example, by placing a cap or other covering over lower opening  416  or by contacting lower end portion  406  against a surface such that lower opening  416  is blocked. With opening  416  blocked, a mixture of polyurethane foam precursors can be poured into chamber  445  through upper opening  414 . As the mixture cures, it provides polyurethane foam seal  450  in chamber  445 . In one embodiment, seal  450  is held in chamber  445  by friction after removing the temporary closure. In another embodiment, the walls of chamber  445  can be pretreated before the mixture is introduced into chamber  445  to increase adherence of seal  450  to the walls of chamber  445 . In still another embodiment, the walls of chamber  445  can include surface features (not shown) such as, for example, grooves or protuberances, to increase the friction between the walls and seal  450  or to otherwise lock seal  450  in chamber  445 . After polyurethane seal  450  is cured, barrier  430  can be passed through upper opening  414  and positioned in contact with seat  420 , if present, or in contact with polyurethane seal  450  of seat  420  is absent, thereby separating bait chamber  440  from chamber  445 . In this embodiment, seat  420  can be present or absent. If seat  420  is present, barrier  430  can be positioned against the upper surface of seat  420  rather than the lower surface of seat  420  as would occur if barrier  430  is loaded into interior space  410  through lower opening  416 . In alternate embodiments, polyurethane foam seal  450  can be separately formed to shape and then inserted into chamber  445 . In such embodiments, barrier  430  can be present or absent. 
     As will be appreciated by a person of ordinary skill in the art in view of the above, the present application provides in one aspect a bait container that defines a lower entry point for access by the targeted pests and a chamber (also referred to herein as polyurethane foam containing chamber  445 ) to hold a polyurethane foam barrier between this entry point and bait positioned above it. The bait container includes a first chamber for containing the bait, an upper end portion defining an upper opening into the chamber, a closure to selectively access and sealingly close the upper opening, a water-impervious side wall and a lower end portion defining a bottom terminus of the bait container and a second chamber below at least a portion of the bait. The second chamber is configured to receive and retain the polyurethane foam to reduce intrusion of water through the lower end portion when the bait container is installed in a selected orientation at least partially below ground. 
     As will be appreciated by a person of ordinary skill in the art, a wide variety of alterations to bait container  400  can be made. For example, in alternative embodiments, polyurethane foam chamber  445  can take on a number of different shapes and configurations, including any type of fluid communication pathway that separates bait chamber  440  from the environment of bait container  400 . In alternate embodiments, chamber  445  can also be positioned at locations other than below bait chamber  440 . In addition, the dimensions and proportions of body  402  can be adjusted to accommodate a wide variety of termite control devices. In addition, the contents of interior space  410  can be altered. For example, pellets  229  can be substituted with other bait materials, or can be omitted, in which case chamber  440  can be filled with polyurethane foam. For example, the bait included in chamber  440  may be composed of a composite bait material as described hereinabove, may be differently composed to target to a different pest type, may include more or fewer cellulosic food material pieces, may include a single food material piece such as a wood or synthetically formed cellulose block, may include no cellulosic food material pieces, may include an attractant with or without pesticide, and/or may be otherwise differently constituted. In addition, the polyurethane foam can be formulated to include an enhancer entrained therein, such as, for example, a cellulose powder or a sugar. 
     A variety of alternative bait containers and bait materials that include a polyurethane foam can be used in other embodiments as stand alone pest control devices or can be used in place of bait container  200  in pest control device  110 . For example, bait material  1  described above and depicted in  FIG. 1  or bait material  4  described above and depicted in  FIG. 2  can be sized and shaped for placement in housing  170  in place of bait container  200  or  400 . In the case of bait materials  1  and  4 , such bait materials can include a pesticide material or, alternatively, a pesticide material can be absent from the bait material. If a pesticide is absent, bait material  1  or bait material  4  can operate to attract termites and establish termite feeding patterns for visual monitoring for possible later administration of a pesticide. If a pesticide is present, bait material  1  or bait material  4  can be positioned in housing  170  to serve both purposes of attracting termites and of delivering a pesticide once termites tunnel into  170  and begin feeding on bait material  1 ,  4 . The presence of polyurethane foam matrix  3  in bait material  1  and polyurethane foam coating  6  in bait material  4 , provides a barrier that prevents cellulosic food material  2  and  5 , respectively, from becoming damp, thereby allowing the bait material to remain positioned in housing  170  for an extended period of time without becoming fouled. 
     Bait container  200  can alternatively be replaced by monitoring device  500  or monitoring device  550  depicted in  FIGS. 17 and 18 , respectively. Monitoring devices  500 ,  550  are similar to bait material  4  depicted in  FIG. 2 , but are formed to include a pest monitoring assembly including sensor subassembly  508  positioned within cellulosic food material member  505 , such as, for example and without limitation, an extruded cellulosic food material, a piece of wood, a termite-edible material for an ESP monitor or a termite-edible material for a Halo monitoring device. Communication circuit subassembly  509  is operably connected to sensor subassembly  508 . This pest monitoring assembly can be configured similarly to pest monitoring assembly  112  depicted in  FIGS. 5-8  or can be configured in other ways as would be contemplated by a person of ordinary skill in the art. Communication circuit subassembly  509  can include electronic components inside a housing. As with bait material  4  depicted in  FIG. 2 , bait material  505  depicted in  FIGS. 17 and 18  can optionally include a pesticide. In an alternative embodiment, food material member  505  can be replaced with polyurethane foam, which can optionally include an enhancer entrained therein, as described above. 
     In the embodiment depicted in  FIG. 17 , polyurethane foam coating  506  provides a uniform barrier around bait material member  505  and communication circuit subassembly  509 . In this configuration, polyurethane foam coating provides a water resistant layer in contact with bait material member  505  that prevents moisture from the environment from contacting bait material member  505  or communication circuit subassembly  509 . In one manner of making monitoring device  500  in which member  505  comprises an extruded cellulosic food material, cellulosic food material member  505  is extruded with sensor subassembly  508  therein. Communication circuit subassembly  509  is then operably connected to sensor subassembly  508 , and communication circuit subassembly  509  is affixed to cellulosic food material member  505 , for example, by being adhered to member  505 . With cellulosic food material member  505 , sensor subassembly  508  and communication circuit subassembly  509  assembled as described, polyurethane foam coating  506  is applied over cellulosic food material member  505  and communication circuit subassembly  509  to provide monitoring device  500 . Communication circuit subassembly  509  is one that is operable to transmit a signal to a remote device, such as a portable interrogator  30  depicted in  FIG. 3 . 
     In the embodiment depicted in  FIG. 18 , polyurethane foam coating  506  provides a barrier around bait material member  505 , but does not extend completely around communication circuit subassembly  509 . In this embodiment, polyurethane foam coating  506  is adhered to communication circuit subassembly  509  such that polyurethane foam coating  506  and communication circuit subassembly  509  operate together to provide a water resistant barrier between bait material member  505  and its environment. With cellulosic food material member  505 , sensor subassembly  508  and communication circuit subassembly  509  assembled, polyurethane foam coating  506  is applied over cellulosic food material member  505  and over a portion of communication circuit subassembly  509  to provide monitoring device  550 . In one embodiment, the portion of polyurethane foam coating  506  in contact with communication circuit subassembly  509  is adhered to communication circuit subassembly to provide a water tight seal therebetween. In another embodiment, a sealing tape (not shown) can be applied over the junction of polyurethane foam coating  506  and communication circuit subassembly  509 . In yet another embodiment, a cap (not shown) can be positioned over communication circuit subassembly  509  and adhered to polyurethane foam coating  506  to provide a water tight seal. In alternatively embodiments, sensor subassembly  508  and communication circuit subassembly  509  can be omitted, and the resulting devices can be used as monitors useful to indicate termite presence by visual inspection. 
     In another embodiment, depicted in  FIG. 19 , bait container  600  has a lower end  606  configured similar to lower end  406  of bait container  400  depicted in  FIG. 12 , and has an upper end  604  that is configured in a similar manner. More specifically, bait container  600  includes barrier member  630   a  shaped and sized to fit in interior space  610  through lower opening  616  to engage lower seat  620   a  and barrier member  630   b  shaped and sized to fit in interior space  610  through upper opening  614  to engage upper seat  620   b . Barriers  630   a  and  630   b  divide interior space  610  of body  602  into three sections. Barrier  630   a  defines a lower boundary of bait containing chamber  640  in body  602 , and barrier  630   b  defines an upper boundary of bait containing chamber  640 . Each of barriers  630   a ,  630   b  are held in place by a polyurethane foam seal (not shown) in a similar manner to polyurethane foam seal  450  described in connection with  FIG. 12 . Bait container  600  can also optionally include a pest monitoring assembly effective to transmit a wireless signal, as described hereinabove. 
     In yet another aspect of the present application, a housing, such as, for example, housing  170  depicted in  FIGS. 9 and 13 , can itself be filled with a composite bait material and thereby can operate as a self contained bait container. For example, to provide a composite bait material in housing  170 , cellulosic food material pieces are loaded into interior space  172  through access end portion  171   a  to at least partially fill housing  170 . After loading cellulosic food material pieces into interior space  172 , a mixture of uncured polyurethane precursors is then introduced into interior space  172  of housing  170  and allowed to flow into the void space created by food material pieces and housing  170 . The uncured polyurethane precursors can be introduced into interior space  172  by pouring through access end portion  171   a . Alternatively, a polyurethane foam precursors can be provided in a delivery system that includes a blowing agent, such as for example, the GREAT STUFF™ polyurethane foam system that is commercially available from The Dow Chemical Company. As the mixture of precursors cures to form a polyurethane foam matrix, it expands to fill additional portions of the void space in interior space  172 , and thereby substantially fill the void space. In an alternative embodiment, cellulosic food material pieces can be omitted, in which case interior space  172  is filled with polyurethane foam, which can optionally include one or more enhancers entrained therein, as described above. 
     To prevent the mixture of polyurethane foam precursors or the polyurethane foam as it cures from escaping housing  170  through passages  174 , passages  174  can be covered before introducing the precursors into housing  170 , for example, by applying a plastic film, such as, for example, shrink wrap, over the sides of housing  170 . In one embodiment, the plastic film is a tape having an adhesive on one side to attach the tape to the outside surface of housing  170 . After the polyurethane foam has cured, and before housing  170  with composite bait material therein is put to use, the plastic film is removed to expose passages  174  and the polyurethane foam. When an adhesive tape is used to cover passages  174 , removal of the tape can operate to roughen the exposed surface of the polyurethane foam, which can increase the acceptance of the composite bait material to termites in the field. In one embodiment, housing  170  also defines a small vent hole (not shown) to allow air to escape as the polyurethane foam cures, thereby equilibrating pressure in housing  170  as the polyurethane foam cures. With reference to  FIGS. 9 and 10 , after the polyurethane foam is cured, removable cap  180  can be affixed to housing  170 , and housing can then be installed in the ground G as shown, for example, in  FIG. 4 . 
     As will be appreciated by a person of ordinary skill in the art, a variety of additional variations and embodiments are contemplated by the present application. For example, additional examples and disclosure of different sensor types, sensor communication techniques, bait material, pesticide, and pest control devices that can be used with any of bait container embodiments described herein may be found in U.S. Pat. Nos. 6,724,312; 7,212,112; and 7,212,129; 7,348,890; and 7,262,702, all of which are incorporated by reference herein each in its entirety. 
     Bait containers according to any of the variations described herein can be installed in different environments, such as at above-ground locations. For above-ground bait containers, bait fouling from extended exposure to environmental moisture is not typically a problem; however, other unique challenges arise. For example, it is generally accepted that cellulosic termite food materials in above-ground bait stations should be moistened in order to attract termites for delivery of pesticides. Cellulosic material in an above-ground bait station, however, tends to become dried out after a relatively short period of time unless it is wetted and then sealed in an air tight envelope or other enclosure, which has the disadvantage of reducing the attractiveness of the bait to termites. In addition, currently available above-ground pest control devices utilize preferred texture cellulose (PTC) bait materials, which are contained in a polyethylene bag that is cut open for termite entry. When termites feed on the PTC in the bag, they also typically impart significant damage to the bag so that the PTC spills from the above-ground station when it is opened, causing a significant mess and inconvenience for users. In another aspect of the present application, there are provided termite baits adapted for above-ground use and above-ground termite control devices that are effective to hold moisture in contact with cellulosic food material over longer periods of time and/or to maintain structural integrity after termite feeding begins. 
     With reference to  FIG. 20 , above-ground termite control device  700  includes housing  710  that defines an interior space and holds composite bait material  727  therein. Composite bait material  727  includes a plurality of cellulosic food material pieces  729  that are palatable to the termite species, embedded within a termite-edible or termite-displaceable polyurethane foam matrix  728 . In one embodiment, the cellulosic food material pieces are cellulose briquettes, such as, for example, RECRUIT IV™ cellulose briquettes, which are commercially available from Dow Agrosciences LLC (Indianapolis, Ind.), or other cellulose briquettes, with or without a pesticide contained therein. Alternatively, cellulosic food material pieces  729  can be composed of a particulate cellulosic material or other cellulosic material as described hereinabove, with or without a pesticide contained therein. In one embodiment, foam matrix  728  is composed of a water-absorbant, open-cell polyurethane foam. In this embodiment, foam matrix  728  provides a water-absorbent scaffold surrounding most or all of cellulosic food material pieces  729  that operates to hold moisture in contact with food material pieces  729 . In another embodiment, foam matrix  728  is composed of a closed-cell polyurethane foam that operates to hold moisture in contact with food material pieces  729 . 
     A bait material of this embodiment is useful in situations where it is desirable for food material pieces  729  to be kept in a moistened state for an extended period of time, such as, for example, for use in an above-ground termite control station. While bait material  727  can eventually become dried out if it remains in a moisture free environment for a long period of time, particularly if the bait is in a hot, dry environment for an extended period of time, polyurethane foam matrix  728  is effective to significantly lengthen the amount of time for food material pieces to become dried in a given environment without being sealed in a water-impervious envelope or other container. 
     As will be appreciated by person skilled in the art in view of the above, in one aspect the present application provides a composite bait material operable to be consumed or displaced by one or more species of termites, the composite bait material comprising a plurality of cellulosic food material pieces that are palatable to said termite species embedded within a matrix comprising a termite-edible or termite-displaceable polyurethane foam. 
     In various alternative embodiments, the polyurethane foam comprises a closed-cell polyurethane foam; the matrix provides a water resistant barrier surrounding at least one of said cellulosic food material pieces; the cellulosic food material pieces comprise a food material selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; the bait material further comprises a pesticide contained within the composite bait material that is toxic to said one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron, hydramethylnon and sulfuramid; the composite material is a monitor or bait for a termite control device; said composite bait material is contained within a bait enclosure; said bait enclosure is adapted to removably fit within a durable, rigid station housing; said composite bait material is contained within a monitor enclosure, said monitor enclosure further comprises one or more monitoring components for signaling termite feeding activity; the polyurethane foam comprises an enhancer entrained therein; the enhancer comprises a food material enhancer; the food material enhancer comprises a member selected from the group consisting of a particulate cellulosic material and a sugar; the food material comprises an alpha-cellulose powder; the food material enhancer comprises a particulate cellulosic material present in the polyurethane foam in an amount of up to about 95 parts per 100 parts polyurethane foam; the particulate cellulosic material is present in the polyurethane foam in an amount of from about 1 to about 75 parts per 100 parts polyurethane foam; the particulate cellulosic material is present in the polyurethane foam in an amount of from about 1 to about 45 parts per 100 parts polyurethane foam; the particulate cellulosic material is present in the polyurethane foam in an amount of from about 5 to about 30 parts per 100 parts polyurethane foam; the particulate cellulosic material is present in the polyurethane foam in an amount of from about 5 to about 25 parts per 100 parts polyurethane foam; and/or the particulate cellulosic material is present in the polyurethane foam in an amount of from about 5 to about 20 parts per 100 parts polyurethane foam. 
     One inventive method of the present application is a method for making a moisture-resistant composite bait material that includes providing a plurality of pieces of a cellulosic food material that is palatable to at least one species of termites in a bait enclosure, wherein the bait enclosure and the plurality of cellulosic food material pieces define a void space therebetween; introducing an uncured mixture of polyurethane foam precursors into said bait enclosure such that said mixture enters at least some of the void space; and allowing said mixture to cure to provide polyurethane foam matrix surrounding at least one of the plurality of said cellulosic food material pieces. 
     In various alternative embodiments, the polyurethane foam matrix is water resistant; said introducing comprises injecting the mixture into the bait enclosure; a blowing agent is used to inject the mixture into the bait enclosure; said introducing comprises pouring the mixture into the bait enclosure; said cellulosic food material comprises a food material selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; said composite bait material further comprises a pesticide that is toxic to the one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; and/or the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam. 
     In another aspect, the present application provides a moisture-resistant composite bait material operable to be consumed or displaced by one or more species of termites, the composite bait material comprising a cellulosic food material member that is palatable to said termite species encapsulated within a termite-edible or termite-displaceable water resistant polyurethane foam coating. 
     In various alternative embodiments, the cellulosic food material member is selected from the group consisting of an extruded cellulosic food material, a piece of wood, a termite-edible material for an ESP monitor and a termite-edible material for a Halo monitoring device; said polyurethane foam coating comprises a closed-cell polyurethane foam; said foam coating provides a water resistant barrier between said cellulosic food material member and its environment; said coating is in contact with said food material member; said cellulosic food material member comprises a food material selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; the bait material further comprises a pesticide contained within the composite bait material that is toxic to the one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon; said composite bait material member is adapted to removably fit within a durable, rigid station housing; at least one monitoring component for signaling termite feeding activity is embedded in said bait material; the polyurethane foam coating comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; and/or the particulate cellulosic material is present in the polyurethane foam coating in an amount of up to about 95 parts per 100 parts polyurethane foam. 
     Another inventive method of the present application is a method for making a moisture-resistant composite bait material that includes providing a cellulosic food material member that is palatable to at least one species of termites; and covering the cellulosic food material member with a coating comprising a polyurethane foam such that said coating provides a water resistant barrier between said cellulosic food material member and its environment. 
     In various alternative embodiments, the cellulosic food material member is selected from the group consisting of an extruded cellulosic food material, a piece of wood, a termite-edible material for an ESP monitor and a termite-edible material for a Halo monitoring device; said cellulosic food material member comprises a food material selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; said composite bait material further comprises a pesticide that is toxic to the one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon; the polyurethane foam comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; and/or the particulate cellulosic material is present in the polyurethane foam in an amount of up to about 95 parts per 100 parts polyurethane foam. 
     In yet another aspect, the present application provides a moisture-resistant termite control device that includes a bait operable to be consumed or displaced by one or more species of termite; and a termite-edible or termite-displaceable water resistant polyurethane foam positioned to separate said bait from its environment; wherein, when said device is exposed to environmental moisture, said foam is operable to provide a moisture resistant barrier between said bait and said environmental moisture. 
     In one embodiment, said bait and said foam compose a composite bait material that is operable to be consumed or displaced by one or more species of termite, the composite bait material comprising a plurality of cellulosic food material pieces contained within a water resistant polyurethane foam matrix. In various alternative embodiments, the termite control device further comprises a pesticide contained within the composite bait material that is toxic to one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon; the cellulosic food material comprises a member selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam; the termite control device further comprises a termite sensing circuit; the device further comprises a container at least partially enclosing said composite bait material, said container defining a chamber for containing the termite bait, and defining apertures for allowing termites to enter said chamber and access said composite bait material; said container includes an upper end portion defining an upper opening into the chamber, and a closure to selectively access and close the upper opening; the device further comprises a termite sensor positioned in the chamber; the termite sensor includes a circuit housing accessible through the upper opening when the closure is open and a sensing substrate downwardly extending from the circuit housing in the chamber; and/or the device further comprises a housing structured for at least partial in-ground installation, the housing terminating at a lower housing end portion located below ground level after the in-ground installation and defining an upper access opening into an interior passage to receive the bait container with the lower end portion passing through the upper access opening before the upper end portion to provide the selected orientation thereof. 
     In another embodiment, said bait comprises a cellulosic food material member that is palatable to said termite species and wherein said polyurethane foam comprises a water resistant coating over said food material member that separates said food material member from the device&#39;s environment. In various alternative embodiments, the termite control device further comprises a termite sensor positioned within said food material member; the termite sensor includes a circuit housing affixed to said food material member and a sensing substrate extending through said food material member from the circuit housing; said food material member has a generally tubular shape defining first and second ends; wherein said circuit housing is affixed to a first end of said food material member; and wherein said sensing substrate extends through said food material member toward said second end; said polyurethane foam coating covers said food material member and said circuit housing, thereby separating said food material member and said circuit housing from said device&#39;s environment; said polyurethane foam coating covers said food material member but does not cover said circuit housing; said polyurethane foam coating is adhered to said circuit housing and said coating and said circuit housing provide a water resistant cover separating said food material member from the device&#39;s environment; the termite control device further comprises an end cap configured to be fitted over said circuit housing and to sealingly engage said foam coating and said coating and said end cap provide a water resistant cover separating said food material member from the device&#39;s environment; the device further comprises a housing structured for at least partial in-ground installation, the housing terminating at a lower housing end portion located below ground level after the in-ground installation and defining an upper access opening into an interior passage to receive the bait; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; and/or the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam. 
     In yet another embodiment, the termite control device further comprises a bait container that includes a first chamber for containing the bait, an upper end portion defining an upper opening into the first chamber, a closure to selectively access and sealingly close the upper opening, a water resistant side wall and a lower end portion defining a bottom terminus of the bait container and a second chamber below at least a portion of the bait, the second chamber configured to receive and retain the polyurethane foam to reduce intrusion of water through the lower end portion when the bait container is installed in a selected orientation at least partially below ground. In various alternative embodiments, a lowermost boundary of the bait is offset from the bottom terminus by at least one centimeter; a lowermost boundary of the bait is offset from the bottom terminus by at least one inch; the bait container includes a tubular body defining a lower opening opposite the upper opening and the device includes a termite-passable barrier separating the chamber into first bait-containing chamber and said second foam-containing chamber; the barrier is positioned between the polyurethane foam and the bait and is configured to allow termite access to the first bait-containing chamber after displacement of a portion of the polyurethane foam in the second foam-containing chamber, and the foam initially closes off the second foam-containing chamber to define an initial water resistant seal and is structured to allow the termites to form one or more passages through the foam to reach the first chamber; the barrier is composed of a material that is edible or displaceable by the termites; said closure includes a handle protrusion structured to manually move the bait container; said closure is in the form of a cap threaded to the container to resealably close the upper opening; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam; the device further comprises a termite sensor positioned in the first chamber; the termite sensor includes a circuit housing accessible through the upper opening when the closure is open and a sensing substrate downwardly extending from the circuit housing in the first chamber; the bait includes a pesticide toxic to termites; the device further comprises a housing defining an internal passage to receive the bait container therein; and/or the housing is structured for at least partial in-ground installation, the housing terminating at a lower housing end portion located below ground level after the in-ground installation and defining an upper access opening into the interior passage to receive the bait container with the lower end portion passing through the upper access opening before the upper end portion to provide the selected orientation thereof. 
     Yet another inventive method of the present application is a method for making a moisture-resistant termite control device that includes providing a bait container having a body that defines an internal chamber and a first opening for passing bait materials into said chamber; inserting a plurality of pieces of a cellulosic food material that is palatable to one or more species of termites into said chamber through said opening, wherein said bait container body and said cellulosic food material pieces define void spaces therebetween; introducing an uncured mixture of polyurethane foam precursors into said chamber through said opening such that said mixture surrounds a plurality of said cellulosic food material pieces; and allowing said mixture to cure to provide a polyurethane foam matrix around said plurality of said cellulosic food material pieces. 
     In various alternative embodiments, the polyurethane foam matrix is water resistant; said introducing comprises injecting the mixture into the bait container; a blowing agent is used to inject the mixture into the bait container; said introducing comprises pouring the mixture into the bait container; said cellulosic food material comprises a food material selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam; said cellulosic food material further comprises a pesticide that is toxic to the one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon; the method further includes placing a termite sensor in the chamber; the opening provides termite access to the chamber; the container body includes a second opening for one or more of inserting the cellulosic food material pieces into the chamber, introducing the polyurethane foam into the chamber or providing termite access to the chamber; the container body includes a second opening, the second opening operable as a vent to allow air to escape from the void spaces during said introducing of the mixture or as the mixture cures to provide a polyurethane foam; the bait container body is tubular and has a first end, a second end and a sidewall extending from the first end to the second end; the first opening is in the first end; the side wall defines one or more additional openings into the chamber; the method further includes, after the mixture is allowed to cure, removing excess foam from the sidewall that escapes from the chamber through the additional openings as the mixture cures; the method further includes, before said introducing, placing a cover over the additional openings in the sidewalls to prevent escape of the polyurethane foam from the chamber through the additional openings during said introducing or as the mixture cures; the cover comprises a shrink wrap cover; the cover comprises a tape having an adhesive on at least one side; the container body includes a second opening in the second end for one or more of inserting the cellulosic food material pieces into the chamber, introducing the polyurethane foam into the chamber or providing termite access to the chamber; the method further includes, before said introducing, covering said second opening to prevent escape of the polyurethane foam from the chamber through said second opening during said introducing or as the mixture cures; and/or said introducing comprises, injecting, spraying or pouring. 
     In yet another aspect, the present application provides an above ground termite control device that includes a housing configured to hold a composite bait material; and a composite bait material contained within said housing, the composite bait material including a plurality of cellulosic food material pieces operable to be consumed or displaced by one or more species of termite and a termite-edible or termite-displaceable polyurethane foam matrix surrounding at least some of the cellulosic food material pieces; wherein the polyurethane foam is effective to hold moisture in the channels to keep the food material pieces moist for an extended period of time. 
     In various alternative embodiments, the polyurethane foam comprises an open-cell polyurethane foam and defines an internal network of channels opening through pores on the surface of the polyurethane foam; the device further comprises a pesticide contained within the composite bait material that is toxic to one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon; the cellulosic food material comprises a member selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; and/or the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam. 
     Still another inventive method of the present application is a method for making an above-ground termite control device that includes providing a bait container having a body that defines an internal chamber and a first opening providing access into said chamber; inserting a plurality of pieces of a cellulosic food material that is palatable to one or more species of termites into said chamber through said opening, wherein said bait container body and said cellulosic food material pieces define void spaces therebetween; introducing an uncured mixture of polyurethane foam precursors into said chamber through said opening such that said mixture surrounds a plurality of said cellulosic food material pieces; and allowing said mixture to cure to provide a polyurethane foam matrix around said plurality of said cellulosic food material pieces. 
     In various alternative embodiments, the polyurethane foam matrix comprises an open-cell polyurethane foam; said introducing comprises injecting the mixture into the bait container; a blowing agent is used to inject the mixture into the bait container; said introducing comprises pouring the mixture into the bait container; said cellulosic food material comprises a food material selected from the group consisting of wood fibers, wood, purified cellulose, microcrystalline cellulose and modified polymeric cellulose; the polyurethane foam matrix comprises an enhancer entrained therein; the enhancer comprises a particulate cellulosic material; the particulate cellulosic material is present in the polyurethane foam matrix in an amount of up to about 95 parts per 100 parts polyurethane foam; said cellulosic food material further comprises a pesticide that is toxic to the one or more species of termite; the pesticide is selected from an immediate action pesticide and a delayed action pesticide; and/or the pesticide comprises a member selected from the group consisting of hexaflumuron, noviflumuron, chlorpyrifos, spinosad, imidacloprid, fipronil, lufenuron, diflubenzuron, flufenoxuron and hydramethylnon. 
     Reference will now be made to the following Examples, which describe laboratory work directed to selected polyurethane foam formulations. It is understood that no limitation to the scope of the application is intended thereby. The Examples are intended to be illustrative, are provided solely to promote a full understanding of the concepts embodied in the application, and are not intended to be limiting or otherwise restrictive as to the nature and scope of the inventions set forth herein. 
     EXAMPLES 
     Example One 
     Testing Moisture Resistance of a Composite Bait Material 
     To test the moisture resistance of a composite bait material including a closed cell polyurethane foam matrix, four bait tubes were made to include cellulosic food material pieces encapsulated in a closed cell polyurethane foam matrix, and the bait tubes were then soaked overnight in a red dye solution to determine the effectiveness of the polyurethane foam matrix to operate as a moisture barrier between the solution and the cellulosic food material pieces. 
     To make the bait tubes, PTC briquettes were poured into four bait tubes similar to bait tube  200  depicted in  FIG. 8 , in which openings  219  and  216  had been covered with a cellophane wrapper. A mixture of polyurethane precursors was then introduced into each tube. For this experiment, the mixture of polyurethane precursors used was the GREAT STUFF™ polyurethane foam product that is commercially available from The Dow Chemical Company. The GREAT STUFF™ product is an expanding foam product that entrains a gaseous blowing agent into the mixture as it is released from its container. 
     After the mixture of polyurethane foam precursors was introduced into the bait tubes and allowed to cure, the cellophane wrapper was removed and the bait tubes were submerged in a red dye solution and allowed to soak overnight. 
     The following day, the composite bait material in each bait tube was observed visually, and was then sectioned using a cutting blade to score the number of PTC briquettes in the composite bait material that had been stained by the dye solution versus the number of PTC briquettes that remained free from dye. The percentage of PTC briquettes in each tube that were not stained by the dye after the overnight soak test are set forth below (wherein the parenthetical ratios for each tube include a numerator identifying the number of briquettes that were not stained and a denominator identifying the total number of briquettes in the tube): 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Tube 1: 
                 59% (83/141) 
               
               
                   
                 Tube 2: 
                 83% (174/210) 
               
               
                   
                 Tube 3: 
                 50% (95/189) 
               
               
                   
                 Tube 4: 
                 70% (130/185) 
               
               
                   
                   
               
            
           
         
       
     
     While some of the PTC briquettes in the composite bait material were stained by the red dye solution, it appears that this staining resulted from openings in the polyurethane foam matrix caused by the PTC briquettes that were positioned against the cellophane wrapping during curing of the polyurethane foam, and channels caused by PTC briquettes in contact with one another, which allowed the dye to pass from one PTC briquette to another. These results establish that the polyurethane foam matrix did provide a moisture barrier between the solution and PTC briquettes that it encapsulated. 
     Example Two 
     Manufacturing a Composite Bait Material Including a Food Material Enhancer 
     A series of composite bait materials were made to include polyurethane foam having alpha-cellulose powder entrained therein. To make these composite bait materials, before mixing the first polyol component with PAPI™ isocyanate, varying amounts of alpha-cellulose powder were mixed into the first polyol component. When the curing of the polyurethane foam was complete, the alpha-cellulose powder was entrained in and dispersed throughout the foam. The amounts of alpha-cellulose included in various examples where selected to produce polyurethane foams having 5 parts alpha-cellulose per 100 parts foam, 10 parts alpha-cellulose per 100 parts foam and 15 parts alpha-cellulose per 100 parts foam. 
     Example Three 
     Termite Penetration/Consumption Testing 
     The composite materials made as described in Example Two were tested against a polyurethane foam having 0 parts alpha-cellulose per 100 parts foam (referred to herein as the “blank foam treatment”) to determine whether termites preferentially consume and/or penetrate polyurethane foam having alpha-cellulose powder entrained therein. 
     One-Way No-Choice Test (Consumption Test) 
     A one-way no-choice test was conducted to determine consumption of polyurethane foams having different levels of alpha-cellulose powder entrained therein by  R. flavipes  termites. Six repetitions of the standard one-way no-choice test with cups was conducted using 100 termites per repetition in Lab Conviron at 28° C. and 60% relative humidity. All samples were provided in the form of ½ inch×1 inch foam blocks and were placed in ½ cut plastic weight boats to allow termites free access to the samples. After 7 days, each foam sample was dried in an oven at 120° C. for 1 hour and placed in a dessicator for at least 2 hours. After drying, the samples were weighed to determine the level of consumption of the samples. 
     Visual inspection of the samples indicated that the termites were visibly feeding on each of the foam samples that included alpha-cellulose powder, but minimal consumption of the blank foam treatment was observed. It appeared that the termites were consuming the foam because there did not appear to be any foam pieces scattered about the bioassay. The results obtained after drying and weighing are provided below: 
                     TABLE 2                  Continuous Force-Feeding (No-Choice) Exposure (7 d). Feeding       Response of  R. flavipes  to Various Polyurethane Foam Formulations       Containing Various Levels of Alpha-cellulose.                         mg consumed after 7 days       Treatment   (mean ± SEM)*               Polyurethane Foam with 25 parts   7.69 ± 0.693 (a)       Alpha-cellulose/100 parts foam       Polyurethane Foam with 10 parts   6.06 ± 1.35 (ab)       Alpha-cellulose/100 parts foam       Polyurethane Foam with 5 parts   3.95 ± 0.8 (b)       Alpha-cellulose/100 parts foam       Polyurethane Foam (blank) with   0.98 ± 0.31 (c)       0 parts Alpha-cellulose/       100 parts foam       Each treatment replicated 6   *Within this column, means followed       times (100 termites per rep).   by same letter are not significantly           different (ANOVA + LSD; p &gt; 0.10).           SEM = Standard Error of the Mean                    
These results confirm that the addition of alpha-cellulose powder to the polyurethane foam increases consumption of the foam by  R. Flavipes  and, in general, the more alpha-cellulose added to the foam, the greater the consumption by the termites.
 
Forced Feeding Test (Penetration Test)
 
     A forced feeding test was conducted in a 3-cup Gladware Bioassay unit to determine the amount of time for  R. flavipes  termites to penetrate the sample materials described above. Because the samples are not easily wrapped around blocks, the test samples were prepared by cutting approximately a one inch square piece of each sample (6 each) and placing each piece on a flat side of a one inch square block of MD-499, which is the aspen wood currently used in SENTRICON® Termite Stations. All remaining sides of the MD-499 block were covered with aluminum foil, securing the sample in place. The block is placed with sample side exposed only through an approximate ¾ inch×¾ inch window opening cut in the bottom center of a 60×15 mm Petri dish. Termites were allowed access to the foam samples only through the window with only the samples exposed. A weight was placed on top of each sample to keep the sample in firm contact with the MD-499 blocks. Samples were checked daily, and a record was made when termites penetrated completely through to the wood block. 
     After five days, the termites were observed to penetrate the foam samples containing alpha-cellulose powder by chewing and/or tunneling multiple holes through the foam samples to the wood block, usually at 2 to 4 locations. Feeding on the blank foam (i.e., polyurethane foam sample without alpha-cellulose) was significantly less than feeding on foam samples containing alpha-cellulose. Results of this test are set forth in the following table: 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Feeding Penetration of Various Polyurethane Foam Samples 
               
               
                 by  R. Flavipes  in a No-Choice Force Feeding Test. 
               
            
           
           
               
               
            
               
                   
                 % Samples Penetrated by Termites, 
               
               
                   
                 Days Post-Infestation 
               
            
           
           
               
               
               
               
               
               
            
               
                 Treatment 
                 Day 1 
                 Day 2 
                 Day 3 
                 Day 4 
                 Day 5 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Polyurethane foam with 
                 0 
                 16.7 
                 50 
                 66.7 
                 83.3 
               
               
                 0 parts alpha- 
               
               
                 cellulose/100 parts foam 
               
               
                 Polyurethane foam with 
                 0 
                 66.7 
                 83.3 
                 100 
                 100 
               
               
                 5 parts alpha- 
               
               
                 cellulose/100 parts foam 
               
               
                 Polyurethane foam with 
                 33.3 
                 83.3 
                 100 
                 100 
                 100 
               
               
                 10 parts alpha- 
               
               
                 cellulose/100 parts foam 
               
               
                 Polyurethane foam with 
                 16.7 
                 66.7 
                 100 
                 100 
                 100 
               
               
                 25 parts alpha- 
               
               
                 cellulose/100 parts foam 
               
               
                   
               
            
           
         
       
     
     Example Four 
     Manufacturing a Composite Bait Material 
     Another composite bait material was made by pouring cellulose pellets into a bait tube similar to bait tube  200  depicted in  FIG. 8 , with openings  219  and  216  covered. A mixture of polyurethane precursors was then introduced into the tube. The mixture of polyurethane precursors was made as follows:
         (1) A first polyol component of a mixture of precursor ingredients for making a polyurethane foam was made by mixing the following ingredients in the identified proportions:
           (i) 50 parts VORANOL 360™ polyol available from Dow Chemical Company   (ii) 50 parts DSD 301.01 polyol available in Europe from Dow Chemical Company   (iii) 3 parts TEGOSTAB D-8404™ surfactant   (iv) 0.2 parts POLYCAT 77™ catalyst   (v) 7 parts water.   
           (2) The first polyol component was mixed with PAPI™ isocyanate to provide a mixture of uncured polyurethane foam precursor ingredients. Addition of the isocyanate initiated the curing reaction.       

     The mixture of uncured polyurethane foam precursor ingredients was then poured in the bait tube, filling void spaces between the cellulose pellets. As the curing reaction proceeded at room temperature, the mixture expanded to fill further portions of the void space. After a curing time of about 5 minutes, curing was complete. 
     Example Five 
     Termite Activity Testing 
     To test the termite activity of a series composite bait material over time compared to a typical wood monitor, bait tubes were made as described above in connection with the embodiment depicted in  FIGS. 5-11 , in which cellulosic food material pieces were encapsulated in a polyurethane foam matrix. In some bait tubes, the polyurethane foam included a food material enhancer entrained therein in varying amounts. Specifically, a series of composite bait material were made by pouring cellulose pellets into a bait tube similar to bait tube  200  depicted in  FIG. 8 , with openings  219  and  216  covered. The cellulose pellets did not include a pesticide, but had been soaked in a sports drink (referred to herein as “EOG”), which operates as a feeding stimulant in the pellets. Various mixtures of polyurethane precursors were then introduced into the tubes. Some of the composite bait materials were made to include polyurethane foam having different amounts of alpha-cellulose powder entrained therein. In composite bait materials including alpha-cellulose powder, when the curing of the polyurethane foam was complete, the alpha-cellulose powder was entrained in and dispersed throughout the foam. The amounts of alpha-cellulose included in various examples where selected to produce polyurethane foams having 5 parts alpha-cellulose per 100 parts foam (referred to herein as “5% alpha cellulose”) and 10 parts alpha-cellulose per 100 parts foam (referred to herein as “10% alpha cellulose”). Other bait tubes were made without alpha-cellulose particles entrained in the polyurethane foam. 
     Bait tube housings similar to housing  170  depicted in  FIGS. 9 and 10  were installed in the ground at various field sites known to have colonies of termites present. Four sites were selected, including a site in Florida having an active colony of  Reticulitermes flavipes  (hereafter, “Site 1”), a site in Florida having an active colony of  Reticulitermes hageni  (hereafter, “Site 2”), a site in Louisiana having an active colony of  Coptotermes formosanus  (hereafter, “Site 3”), and a site in Mississippi having an active colony of  Reticulitermes flavipes  (hereafter, “Site 4”). At each site, multiple replications of the test were performed. In each replication, four (4) housings were installed at locations equidistant from feeding termites, and four different bait tubes were installed in the four housings, one including a composite bait material including polyurethane foam (without alpha-cellulose entrained therein) and cellulose pellets (hereinafter “Test Material 1”), a second including a composite bait material including 5% alpha cellulose polyurethane foam and cellulose pellets (hereinafter “Test Material 2”), a third including a composite bait material including 10% alpha cellulose polyurethane foam and cellulose pellets (hereinafter “Test Material 3”), and a fourth including a conventional wood monitor, either MD-499 or southern yellow pine (hereafter “Wood Bait Material”). 
     After installation of the bait tubes as described above, the tubes were inspected after 90 days and after 180 days for the presence of termite activity in the tubes. The percent of tubes showing activity at each site at 90 days and at 180 days are set forth in the following Tables 4 and 5, respectively: 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Bait activity at 90 days for trials with polyurethane foam bait 
               
               
                 tubes tested against  Reticulitermes  spp. In Mississippi and Florida 
               
               
                 and against  Coptotermes formosanus  in Louisiana 
               
            
           
           
               
               
               
            
               
                   
                 Treatment 
                 Percent of Tubes with Active Termites 
               
               
                   
                   
               
            
           
           
               
            
               
                   Reticulitermes flavipes  - Florida (Site 1) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 0 
               
               
                   
                 Test Material 2 
                 0 
               
               
                   
                 Test Material 3 
                 0 
               
               
                   
                 Wood Bait Material 
                 50.0 
               
            
           
           
               
            
               
                   Reticulitermes hageni  - Florida (Site 2) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 9.1 
               
               
                   
                 Test Material 2 
                 9.1 
               
               
                   
                 Test Material 3 
                 9.1 
               
               
                   
                 Wood Bait Material 
                 18.2 
               
            
           
           
               
            
               
                   Coptotermes formosanus  - Louisiana (Site 3) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 75.0 
               
               
                   
                 Test Material 2 
                 75.0 
               
               
                   
                 Test Material 3 
                 81.3 
               
               
                   
                 Wood Bait Material 
                 43.8 
               
            
           
           
               
            
               
                   Reticulitermes flavipes  - Mississippi (Site 4) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 27.3 
               
               
                   
                 Test Material 2 
                 36.4 
               
               
                   
                 Test Material 3 
                 36.4 
               
               
                   
                 Wood Bait Material 
                 18.2 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Bait activity at 180 days for trials with polyurethane foam bait 
               
               
                 tubes tested against  Reticulitermes  spp. In Mississippi and Florida 
               
               
                 and against  Coptotermes formosanus  in Louisiana 
               
            
           
           
               
               
               
            
               
                   
                 Treatment 
                 Percent of Tubes with Active Termites 
               
               
                   
                   
               
            
           
           
               
            
               
                   Reticulitermes flavipes  - Florida (Site 1) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 10.0 
               
               
                   
                 Test Material 2 
                 20.0 
               
               
                   
                 Test Material 3 
                 10.0 
               
               
                   
                 Wood Bait Material 
                 70.0 
               
            
           
           
               
            
               
                   Reticulitermes hageni  - Florida (Site 2) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 27.3 
               
               
                   
                 Test Material 2 
                 27.3 
               
               
                   
                 Test Material 3 
                 45.5 
               
               
                   
                 Wood Bait Material 
                 27.3 
               
            
           
           
               
            
               
                   Coptotermes formosanus  - Louisiana (Site 3) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 87.5 
               
               
                   
                 Test Material 2 
                 93.8 
               
               
                   
                 Test Material 3 
                 87.5 
               
               
                   
                 Wood Bait Material 
                 68.8 
               
            
           
           
               
            
               
                   Reticulitermes flavipes  - Mississippi (Site 4) 
               
            
           
           
               
               
               
            
               
                   
                 Test Material 1 
                 27.3 
               
               
                   
                 Test Material 2 
                 36.4 
               
               
                   
                 Test Material 3 
                 45.5 
               
               
                   
                 Wood Bait Material 
                 36.4 
               
               
                   
                   
               
            
           
         
       
     
     While multiple embodiments of the invention have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the selected embodiments have been shown and described and that all changes, modifications and equivalents that come within the spirit of the invention as defined herein or by any of the following claims are desired to be protected. Any theory, mechanism of operation, proof, or finding stated herein is meant to further enhance understanding of the present application and is not intended to make the present application in any way dependent upon such theory, mechanism of operation, proof, or finding. It should be understood that any use of the word preferable, preferably or preferred in the description above indicates that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one,” “at least a portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.