when grasshopper densities are 15-22/square yard, well above the threshold at which treatment programs are typically considered. Once grasshopper density declines to about 2/square yard, Nosema is no longer effective (Anon., 1987b). Henry and Oma (1981) found that fat body, neural, andothertissuesaredainagedbyNosema. Development rates, activity levels, and fecundity are usually reduced, while cannibalism often increases. If large numbers of spores are ingested relatively early in grasshopper de- velopment, the deleterious effects of the disease may be more pronounced, although death may occur weeks later. In one optimal scenario, application of 1.12- 1.68 kgofwheatbranperhectarecontaining 1.6 x 10'to 2.3 x 101 spores, distributed while Melanoplus sanguinipes is predominantly in instar 3, may produce 50-60% mortality in 4-6 weeks; survivors could have infection levels of 35-409'o (Henry and Oma, 1981). 'Mus, applied by itself, Nosema does not provide short- term control of grasshoppers. Promoters of the product claim that long-term suppression could be realized (Wright, 1985; Onsager, 1987); however, performance -   of the product in a variety of large-scale field tests since 1975 has not been consistent, well defined, nor easily quantified (Onsager, 1987). Henry and Onsager (1982) concluded that Nosema - couldbepotentiallyusefulinanintegratedpestmanage- ment program for grasshoppers on rangeland. Wright (1985) states that because of its relatively high cost per - acre, Nosema would be most useful where environmen- tal concerns were of primary importance. Nosema has been connnercially marketed as a rangeland pest control product since the mid-1980s. It was first incorporated into an APHIS grasshopper management program in 1986 after undergoing extensive research trials for over a decade. In 1986, approximately 25,000 acres in the - westemU.S.weretreatedwithNosemaforgrasshoppers. Research continues on additional species of Nosema, including N. acridophagus Henry and N. cuneatum Henry,thatappeartobemorepathogenicthanN. locustae (Capinera and Sechrist, 1982b). Development of these products as biological insecticides has been slowed by problems with host insect culture; these other Nosema species apparently kill their hosts so rapidly that few spores can beharvested. The discovery thatcom earworm, Helicoverpa zea (Boddie), could produce relatively large numbers of spores without killing the caterpillars sug- gests a possible new route for research and potential commercial development (Henry et al., 1979). Cooperative Grasshopper Control Programs NVhile various agencies in the western states had attempted to organize grasshopper control campaigns since the turn of the century, the federal government became acutely aware of the magnitude of rangeland grasshopper problems in the 1930s. Grasshopper sup- pression over very large areas would require synchro- nized and cooperative efforts from land managers; the individual rancher treating pest problems alone would have little or no impact on pest populations even if the control program were exceptionally thorough. In recent years, the USDA-APHIS and state depart- ments of agriculture have agreed to conduct cooperative surveys and, if warranted, to implement grasshopper population control programs on both private and gov- ernment-owned land. Since 1986, APHIS' preferred alternative, an inte- grated pest management program (IPM) for grasshop- pers on rangeland, has been developed to incorporate elements of an interagency IPM pilot project for long- range programmatic consideration. Elements of this rangeland IPM program are outlined in detail in the Environmental Impact Statement (EIS) (Anon., 1987b). Underthe IPM alternative, inalathion, carbaryl, acephate sprays, carbaryl bait, andnosema locustae bait would be available for particular control projects; research would continue on other chemical and biological methods and on culturallmechanical methods. Databases developed from survey results could be used to enhance outbreak prediction capabilities. As new methods become opera- tional, APHIS would conduct environmental analyses tied to the current EIS for consideration in its program. The EIS examines potential impacts on soils, vegeta- tion wildlife, water quality and aquatic systems, human health and worker safety, socioeconon-tics, historic and cultural resources, visual resources, and noise levels. Any potential adverse impacts would theoretically be avoided through adherence to operational procedures and mitigation measures provided in the document. To facilitate paperwork processing and to decrease re- sponse time in the event of a cooperative control pro- gram in a given county, a biological assessment is made of any endangered or threatened species of wildlife found within the county. Protective measures such as leaving an untreated buffer zone around the species habitat may be required to protect any species of con- cern. These documents may be reviewed and updated annually or as conditions require. Widespread outbreaks of grasshoppers are usually preceded by several years of gradual population buildup associated with nilld spring weather and a low incidence of disease, parasites, and predators. These conditions, plus late summer rains that provide adequate food for egg-laying females, usually result in an outbreak. Popu- lations normally collapse in about a year when weather conditions are poor for egg-laying and grasshopper development, and also when parasites, predators, or disease levels have reached their maximum levels.