Bait station

A bait station device for the control of ants, especially of Pharaoh's or Sugar Ant.

The present invention concerns a bait station device for the control of 
ants, especially of Pharaoh's or Sugar Ant. 
Pharaoh's or Sugar ants [Monomorium pharaonis (L)] have become a major pest 
due to the combination of their propensity for indoor infestation and 
synanthropic existence as well as an ability to survive pest control 
techniques. 
They tend to infest areas kept permanently heated such as food stores, 
households, hospitals and the like with the potential for causing health 
and sanitary problems due to their apparent ability to act as vectors for 
infectious agents and thus spread disease. The use of classic insect toxin 
formulations has proven inadequate to control these ants. This is due to a 
variety of reasons based on the biological and sociological 
characteristics of these ants. Colonies are usually polygynous, supporting 
anything up to tens of thousands of queens. The worker ants appear to have 
the capability to quite quickly recognize toxins both on surfaces and in 
baits and avoid them. Workers will often pick up eggs, larvae, pupae and 
the like and move them to an unaffected area and set up a new colony. 
Additionally, the fact that few foragers are actually killed and the high 
level of other survival factors such as high reproduction rate, frequent 
colony division, low intercolony antagonism, etc., contribute to the 
problem. 
Many attempts have been made to effectively control pharaoh ants, for 
example employing substances toxic to the ants. These methods although 
having initial success suffer from a return of ant infestation a few weeks 
following treatment. Improvements by employing highly attractive baits 
whilst showing increased success nevertheless require repeat treatments 
and constant vigilance. 
In trying to overcome this problem attempts were made to control pharaoh 
ants using insect growth regulators (IGRs) such as methoprene. Whilst 
these products are successful in achieving full and lasting control it may 
take up to 20 weeks for this control to manifest itself requiring 
additional quick knock down treatments with toxins (insecticides) for 
initial control. Each of these methods are costly in terms of material 
used, labor intensive (repeat treatments) and complicated. 
Examples of literature describing such previous attempts include: Burden 
et.al., J. Med. Ent., 12/3, pp 352-3 (1975); Hrdy et.al and Edwards, 
International Congress of the International Union for the Study of Social 
Insects, Wageningen, The Netherlands, 1977; Newton, Int. Pest Control, 
Sep./Oct. 1980, pp 112-114; Edwards et. al., Regulation of Insect 
Development and Behavior, Warsaw, Poland, pp 769-778. 1981; Wilson et.al., 
Pest Control, Mar. 1981, pp 14-16; Rupes et.al., J. Hyg. Epidem. Microb. 
Immun., 27/3, pp 295-303 (1983)., Granovsky, Pest Management, May 1983, pp 
11-16; Granovsky et.al., Pest Control Technology, Mar. 1983, pp 30-34. 
Products previously recommended against Pharaoh ants include MAXFORCE.RTM. 
(a.i. hydramethylnon), PHARORID.RTM. (a.i. methoprene). 
It has now surprisingly been found according to the present invention that 
effective, long lasting control without rebounding infestation can be 
achieved by presenting the ants with a combination of an insect growth 
regulant (IGR) bait and insecticide bait in such a way that the worker 
ants have to forage their way through the IGR bait to reach the 
insecticide bait. 
In this way foraging worker ants will transport back to nests for feeding 
of the colony IGR bait and upon exhausting the available IGR bait will 
themselves ingest the insecticide bait causing their rapid mortality 
following contamination of the colony with IGR bait. In this manner 
initial exposure would be only to IGR allowing queen a broad exposure and 
ultimately decimation of the colony followed by secondary exposure to 
insecticide leading to rapid death of worker ants thus preventing them 
carrying out the normal defense measures. 
The invention therefore concerns a pesticidal device which comprises a 
housing containing an insecticidal bait and an insect growth regulant bait 
and having therein at least one opening whereby said insecticidal bait is 
so disposed within said housing that it may only be reached from said 
opening by removing or passing through said insect growth regulator bait. 
The devices according to the invention thus provide ready to use control 
measures for one-off treatment. 
It will readily be appreciated that such a device will be suitable for 
combatting ants of any species however, it is particularly suited for 
combating pharaoh ants. 
The precise nature of the insecticide, IGR and bait is not critical to the 
functioning of the device. 
Thus suitable insecticides are those which are known to be effective on 
ants. Examples of such insecticides or toxins include boric acid, 
diazinon, bendiocarb, hydramethylnon, or mixtures of suitable insecticides 
such as these. 
Suitable IGRs include those known to affect the development and growth of 
insects especially ants and in particular to prevent their survival. 
Examples include, methoprene, hydroprene, kinoprene, fenoxycarb, or 
mixtures of suitable IGRs such as these. 
Baits suitable for use in preparation of insecticide- and IGR-baits are 
those conventionally used in ant baits, for example e.g. peanut butter, 
fishmeal, honey, sugar, mint apple jelly, strained egg yolk, liver, sponge 
cake, etc. or mixtures thereof. Such baits may also contain attractants 
such as trail pheromones, quene pheromones, neocembrene-pharoes ant, fire 
ant pheromones,(E)-6-(1-pentenyl)-2H-pyran-2-one, 
tetrahydro-3,5-dimethylbutyl-2H-pyran-2-one, and dihydroactindiolide. 
Bait material is mixed separately with IGR and insecticide whereby 
different baits may be used for the two types of active ingredient. For 
example, it may be desirable to employ a slightly more attractant bait for 
the insecticide to increase the incentive for the worker ants to work 
their way through the IGR bait. Baits are preferably not intermingled but 
are preferably disposed in contact with each other in the device. 
Further examples of suitable insecticide, IGRs and baits are contained in 
the references listed above the contents of which in this respect are 
incorporated by reference. 
The precise nature of the housing is also not essential to the invention 
provided that it is so arranged as to allow the insecticide bait to be 
placed in such a manner as to be reachable only through or by removal of 
the IGR bait. 
Thus truncated cylindrical housings such as those used in commercially 
available devices having a series of substantially axially orientated 
passages leading from the outer circumference of the cylinder to the 
center may be employed whereby the insecticide bait is placed at the 
center of the housing and the IGR bait used to fill the axial entry 
passages. 
Alternatively and preferably tubular housings may be used which may be 
opened at one end and closed at the other whereby insecticide bait is 
filled in first to the closed end of the tube followed by IGR bait to 
close off access to the insecticide bait. The tube may also be open at 
both ends and contain insecticide bait surrounded on both ends by IGR 
bait. 
When referring to the devices according to the invention as having at least 
one opening it will be readily appreciated that such openings may be 
sealed until immediately prior to putting the device to use in order to 
preserve the integrity and stability of the bait and that such devices 
with sealed openings are intended to be encompassed by the invention. 
The housing may be made from any materials which are convention for such 
devices. The material will be chosen so as to be compatible with the 
insecticide and IGR to be employed and be of such thickness and 
consistency as to prevent loss of active ingredient, and other bait 
substituents and to prevent absorption and/or loss of moisture from the 
bait composition. Examples of such materials include e.g. 
polyvinylchloride, polyethylene terephthalate, high- and low-density 
polyethylene, polypropylene, glass and the like. Tubes can for example be 
similar to those used for the imbibing of soft drinks and constructed from 
heatsealable plastic material such as low-density polyethylene. Other 
suitable materials will be evident to those skilled in the art. 
The size of the device is not critical and will usually be dictated by 
convenience of packaging and handling and will be large enough to contain 
sufficient bait but sufficiently small to allow easy concealment. A 
cylindrical device such as described above and below would conveniently be 
of diameter between 3 and 6 cms. A tubular device would for example have a 
diameter of e.g. 3 to 7 mm and a length of 6 to 18 cms depending on amount 
of bait/a.i. required. 
Such devices can be used in any area where control of ants, especially 
pharaoh and in desired e.g. single and multi-family dwellings, 
restaurants, zoos, nursing homes, pet shops, etc. 
They may simply be placed on the ground or on counter-tops in the relevant 
areas or conveniently fixed to the underside of surfaces such as 
counter-tops, tables, widow-sills and the like using for example a strip 
of two-sided adhesive tape which may be pre-attached to the packaged 
stations. 
The number and placing of the devices will depend upon the size and layout 
of the area to be treated and the efficacy of the a.i.'s employed and will 
lie within the experience of the man skilled in the art. For example, the 
total number of bait stations may vary from 25 for 0-100 ants 
monitored/2500 sq. ft. to 200 for 500-1000 ants/5000 sq. ft.

The device comprises a hollow tube 1 which may be made of plastic material 
and preferably clear thermoplastic material such as a drinking straw-like 
tube. Into this tube 1 is filled in the embodiment shown in FIG. 1 
insecticide bait 3 followed by IGR bait 2 to enclose the insecticide bait 
for example by injection. (Examples of suitable bait composition are given 
hereinafter.) Following introduction of the bait compositions the tube is 
sealed at each end 4 for example by heat sealing. In this form the device 
may be stored until ready for use. 
In use the end 5 of the tube 1 which is proximal to the IGR-bait 2 is cut 
open to expose the bait. Foraging ants attracted by the bait will enter 
the tube and collect IGR bait which they take back to the nest thus 
exposing queens and brood. Upon exhaustion of IGR-bait workers collect and 
ingest insecticide bait causing rapid mortality. 
The alternative arrangement shown in FIG. 4 differs from the specific 
embodiment above in that the insecticide bait 3 is placed in the middle of 
the tube and is followed by IGR-bait 2 at each end to enclose the 
insecticide bait 3. The ends 4a are then sealed as described above. In use 
both ends 5a of the tube are cut open to allow access to the IGR bait. 
The following examples further illustrate the invention without in any way 
restricting its scope. 
EXAMPLE 1 (Bait Formulations) 
______________________________________ 
W/W % 
______________________________________ 
i) IGR Bait 
Ingredient 
PHARORID (10% R,S-Methoprene) 
4.8% 
(0.48% 
R,S-Methoprene) 
Peanut Butter, Creamy 47.6% 
Honey 47.6% 
100.0% 
Insecticide bait 
Ingredient 
ii)a) 
Boric Acid (100% boric acid) 
4.5% 
Peanut butter, Creamy 51.0% 
Honey 38.2% 
Water 6.3% 
100.0% 
b) Boric Acid (100% boric acid) 
4.5% 
Peanut butter, Creamy 44.6% 
Honey 44.6% 
Water 6.3% 
100.0% 
______________________________________ 
EXAMPLE 2 (Efficacy) 
Field Trial 
The trial is carried out in single family homes with existing Pharaoh Ant 
infestation. 
Materials 
The test devices are straws with both boric acid and methoprene. These were 
prepared by placing (via syringe) one gm of boric acid bait (Ex. 1 ii)b)) 
in the center of each straw, then with a second syringe 0.5 gm of 
methoprene bait (Ex. 1 i)) at each end of the straw touching the boric 
acid bait. The ends of each straw are then sealed to be opened at time of 
treatment. 
Population Monitoring 
The ant population is monitored before treatment by counting the ants 
around peanut butter placements. Each placement is ca one gm peanut butter 
in a plastic weigh boat. (1.75 in square.) These are placed in the 
immediate area of ant activity. The recommended placement is five stations 
in kitchen, two stations in each bathroom, and one station in each of the 
other rooms. The monitoring stations are left overnight and counts of the 
ants present on and around each station recorded. 
This monitoring is done twice pre-treatment and once/week post treatment 
until ant activity ceases or until four months post treatment. The 
locations of the monitoring sites are marked and numbered. During 
treatment, one to four (based on number of ants) of the bait stations are 
opened and placed at each marked monitoring site, and the weekly post 
treatment ant counts are made around these. The bait stations in the 
marked monitoring sites are used post treatment instead of the trays with 
peanut butter. 
TREATMENT 
The total number of bait stations for treatment is based on the number of 
ants counted in the pretreatment survey. The following guidelines are 
used. 
______________________________________ 
GUIDE FOR DETERMINING 
NUMBER OF BAIT STATIONS 
Total Structure Sq. Ft. 
No. Ants 2500 5000 
______________________________________ 
0-100 25 50 
Pretreatment 
100-500 50 100 
Counts 500-1000 100 200 
______________________________________ 
The majority of the bait stations are placed in areas having the most ant 
activity. A few stations are placed in each room of the house. Several 
stations are put around each source of water within the structure. 
RESULTS 
The results of the above tests at three locations are shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Location Weeks Post Treatment 
__________________________________________________________________________ 
2 3 4 6 7 8 9 11 13 15 17 18 
__________________________________________________________________________ 
(1) Total Number Ants 
92 151 
28 19 0 0 0 0 0 0 0 0 
Pretreat Total = 72 
Percent Reduction 
(28) 
(110) 
66 47 100 
100 
100 
100 
100 
100 
100 
100 
__________________________________________________________________________ 
1 2 3 5 7 9 11 11 13 15 17 18 
__________________________________________________________________________ 
(2) Total Number Ants 
156 
126 
75 0 0 6 0 0 0 0 0 0 
Pretreat Total = 691 
Percent Reduction 
77 82 
89 100 
100 
99 100 
100 
100 
100 
100 
100 
__________________________________________________________________________ 
1 2 3 5 7 9 11 11 13 15 17 18 
__________________________________________________________________________ 
(3) Total Number Ants 
220 1 0 0 3 0 0 0 0 0 0 
Pretreat Total = 691 
Percent Reduction 
54 100 
100 
100 
99 100 
100 
100 
100 
100 
100 
__________________________________________________________________________ 
CONCLUSION 
As can be seen from the results total control of ant infiltration within 5 
to 7 weeks without subsequent rebound activity which indicates destruction 
of the colony.