are rarely considered for treatment programs. Not only have they already donetheirmaximum damageto range, but also they probably have already oviposited and are senescent. A annual pictorial summary of results color- coded for subeconomic (3-7 grasshoppers/square yard) and economic populations (8 or more grasshoppers/ square yard) is compiled each winter with data from all cooperators by USDA state offices. Copies of these maps are usually available in early spring through the NMSU Cooperative Extension Service, the New Mexico Department of Agriculture, or the U.S. Department of Agriculture. Surveyors can consult these annual maps to make any necessary adjustments in their plans for nymphal surveys the fo    'Ilowing spring. "Sentinel survey sites" have also been established to track population dynamics of grasshoppers in selected sites in New Mexico. In 1985, 91 of these sites were permanentlyestablishedbyUSDA-APHIS-PPQinparts of counties known to have persistent problems with large numbers of economically significant grasshop- pers; this effort was part of a larger one for western and Midwestern states to develop some long-term, detailed observations of grasshopper species interactions and developmental dynamics. Not only are counts of the various species or types of grasshoppers taken during each of these site visits, but also specimens for identifi- cation. These sites are visited four times during the season, with first visits occurring very early in the spring in the more southern locations with lower elevations, and later in the year for those that are farther north or higher. T@ree visits primarily involve nymphal grass- hoppers, while the fourth is timed for assessing the damage potential of adult grasshoppers. Insecticidal Control of Grasshoppers Synthetic insecticidal baits or foliar treatments have been used for grasshopper control in the western U.S. sincetheearly 1900s. Insecticideingredients andformu- lations used for grasshoppers have necessarily changed over time, reflecting changes in availability, economics, application methods, general safety, efficacy, environ- mental concerns, and survey methodology. In Colorado and elsewhere in the western U.S., baits were the most widely used formulations ftom about 1913 until the late 1940s (Capinera and Sechrist, 1982b). An inexpensive agricultural byproduct such as wheat bran, rolled barley, or fndt pomace was used as the food attractant and carrier. Arsenical insecticides were used as toxicants through the 1930s and early 1940s. To reduce costs, cheap dry diluents such as corncob grits or sawdust were milled with the toxicant and carder. Small amounts of water or an oil helped bind the toxicant to the dry mixture; addition of a small amount of molasses to the bait usually increased acceptance by the grasshop- pers. More recently carbaryl has been used as the toxi- cant in baits, but the formulation process remains much the same. Baits have been applied by various kinds of ground rigs and, since the 1970s, by airplane. Because applica- tion rates are usually 1-1.5 pounds of formumon per acre, large-scale control programs present logistical problems in obtaining the required volume of formu- lated material, transporting it to the treatment site, stor- age, and application. Other disadvantages in using baits include: they may not be equally attractive to all grass- hopper species in a local pest complex; some individuals do not find the bait or consume only a sub-lethal dose; and some individuals may be molting instead of eating when the active ingredient in the bait is most effective (Onsager et al. 1980). Grasshoppers vary significantly not only in bait acceptance but also in susceptibility to commonly used insecticides (McDonald, 1967). On the other hand, because baits are relatively selective for grasshoppers, they minimize the hazard to various natu- ral enemies of grasshoppers and non-target organisms. 'Mus, baits may be a preferred formulation for environ- mentally sensitive areas such as roadsides or urban lots. Mukerji et al. (I 98 1) reported that less active ingredient was needed to provide a satisfactory level of grasshop- per control with bait versus a liquid formulation. Use of liquid insecticide formulations began in the late 1940s with chlorinated hydrocarbons such as aldrin and toxaphene. Although both materials were effective and economical, and their residuals were comparatively long lasting, concern over their appearance in the food chain caused them to be replaced with short-term re- sidual materials such as malathion and acephate (both organophosphates) and carbaryl (a carbamate). Malathion is most commonly used undiluted and at very low rates - a specific formulation and application technique known as "ULV" or "ultra-low volume." It usually is the least expensive insecticide labeled for grasshoppers on a variety of crops and rangeland. Malathion is especially effective on grasshoppers at temperatures above 90OF when conditions are dry (Onsager, 1978). Carbaryl has been formulated as a bait (described above) and as a liquid applied in a mixture of oil and water. The oil enhances toxicant adhesion to foliage, while the water aids in product dilution. This toxicant has proven more effective on grasshoppers when weather conditions were cooler or wetter than recommended on the malatliion label (Onsager, 1978). Depending upon the study, effective carbaryl residues have persisted as long as 21 days post treatment (Lloyd et al., 1974, Onsager, 1978), although 15 days is considered normal (Anon., 1987b). Acephate has demonstrated good residual control of