Rangeland in the western United States is a valuable agricultural resource for livestock production and provides an important habitat for wildlife. Grasshoppers and Mormon crickets (hereafter, referred to collectively as grasshoppers) are natural components of this ecosystem. However, their populations can reach outbreak levels and cause serious economic losses to rangeland forage, especially when accompanied by a drought.
Not all grasshopper species significantly damage rangeland forage, so action to protect rangeland resources is not always required when grasshopper populations increase. However, a rapid and effective response is required when a grasshopper outbreak develops and threatens rangeland forage. During such an event, Federal land management agencies, State agriculture departments, county and local governments, private groups, and/or individuals can request assistance from the U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) to suppress rangeland grasshopper populations. Under the Plant Protection Act, APHIS has the authority, subject to funding availability, to treat Federal, State, or private lands that have economically significant infestations of grasshoppers.
Grasshopper and Mormon Cricket Biology
Grasshoppers and Mormon crickets are closely related insects that belong to the Order Orthoptera. Nearly 400 grasshopper species inhabit the 17 western States involved in APHIS' grasshopper program, but only a small percentage are considered pest species. Anywhere from 15 to 45 species of grasshoppers can be found in a particular rangeland ecosystem, and economic damage usually occurs as a result of grasshoppers increasing in number.
Mormon crickets ( Anabrus simplex) are flightless, shield-backed katydids. Although they do not fly, Mormon crickets are highly mobile and capable of migrating great distances. They move in wide bands by walking or jumping, and may devour much of the forage in their path.
Both insects damage grasses and other vegetation by consuming plant stems and leaves. Their feeding causes direct damage to plants' growth and seed production, thus reducing valuable livestock forage. Other effects of these pests include: soil erosion and degradation, disruption of nutrient cycles, interference with water filtration, and potentially irreversible changes in the flora and fauna of the rangeland ecosystem. In addition, some populations that develop on rangelands can invade adjacent cropland where the value of crop plants is much higher than rangeland grasses.
APHIS' Grasshopper Program
APHIS conducts surveys for grasshopper populations on rangeland in the western United States, provides technical assistance on grasshopper management to landowners and managers, delivers public outreach and education programs, and may cooperatively suppress grasshopper populations when direct intervention is necessary. APHIS treats grasshoppers only upon request and after determining that treatment is warranted. In some cases, APHIS rangeland treatments protect not only the rangeland, but also reduce the likelihood that the grasshoppers will move into crops and other lands that border rangeland.
APHIS surveys grasshopper populations in the following western States: Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, and Wyoming. Survey information is used by APHIS and land managers and owners to assess whether treatments may be warranted. Treatment must be requested by a Federal land management agency, State agriculture department, county or local government, private group, and/or individual that has jurisdiction over the land before APHIS can begin to consider a treatment.
Upon request, APHIS would visit the site and assess various factors relevant to the infestation to determine whether action by APHIS is warranted. These factors include, but are not limited to, the pest species, biological stage of the species, timing of the treatment, treatment and chemical options, cost benefits of conducting the action, and ecological considerations. Grasshopper surveys, conducted at certain times of the year, may show the potential for large grasshopper populations. Based on survey results, county, State, and Federal officials and/or rancher groups may initiate early coordination of local programs and request APHIS assistance in a timely and effective cooperative effort.