Grasshopper Infestations on the Rise Again

August 7, 2002

As drought blankets much of the western U.S. and Canada, so do grasshoppers, Mormon crickets, and other associated bugs. The cyclical insect infestations, which are occurring in pockets in every state west of the Mississippi and in Alberta, Saskatchewan, and Manitoba, range from light to very severe.

The swarms are sparking stories about damage to crops and ornamental plants, concerns about pesticide use and land management practices — and quirky angles such as grasshoppers eating paint off the sides of houses and people driving over swarms so dense they sound "like a popcorn popper full of green kernels." Problems are likely to worsen over the next month or two, until rains or frosts hit.

Since 1993, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has had no money appropriated for tracking infestations. But, sparked in part by pressure from the Utah delegation, it received $3.6 million this year to survey lands in the West, and discovered infestations substantially different than predicted with its computer model. The July 25, 2002, survey is available from APHIS's Anna Cherry, 301-734-7253. Predictive model. Grasshopper infestations can occur in the East, but are not a focus of the department.

The 2002 survey reflects relatively low populations for Utah, although the state declared a state of agricultural emergency on May 7, 2002, due to grasshoppers and Mormon crickets, and USDA Secretary Ann Veneman issued a disaster designation on July 1, 2002.

Such designations can help affected people get low-interest loans, which may be used in part to buy pesticides. But pesticides are effective only at certain times, and can kill many beneficial creatures. To reduce pesticide use, some applicators are adopting a method called "Reduced Agent and Area Treatments." University of Wyoming, Jeffrey Lockwood, 307-766-4260, Grasshopper Encyclopedia. (For the infestations themselves, Lockwood is working on a predictive model that he hopes will be more accurate than USDA's.)

Other control methods that can work at certain times and have their own tradeoffs include baits, tilling of croplands, and modified grazing practices. But controls may not always be desirable, since some of the hundreds of species of grasshoppers eat several of the invasive weed species that are spreading throughout the country.

In areas where grasshopper infestations remain high, other bugs such as blister beetles can blossom. They feed on grasshopper eggs, but can harm animals that eat them.

Background: Texas A&M, Carl Patrick, 806-677-5600.

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