CITY FOLKS RARELY think of the grasshopper as a public enemy. Even most country-dwellers' livelihoods are little influenced by an insect best known for its erratic leaps and bounds. But grasshoppers, like other insects, do have a bite of something to eat every so often. And thus it is that in large numbers they can be as devasting to crops and grazing lands as their close relative, the locust. Millions of grasshoppers now are infesting parts of at least five Plains states, stripping the land of crops and grass for animal grazing. If unchecked, their foraging could ruin thousands of farmers and ranchers in Oklahoma, Nebraska, Kansas, Colorado and Wyoming. Already, estimates of the present damage run into the millions of dollars.

Grasshoppers breed at an extraordinary rate (a female insect can lay up to 300 eggs during one reproductive cycle), but in the Plains states their numbers usually have been effectively controlled by parasites and predators and by man-made pesticides. That system of checks and balances was skewed last year, first by a lengthy drought, which killed off grasshopper-eating insects and animals, and then by ensuing heavy rains, which provided perfect incubation conditions for the grasshopper eggs. The result: Millions of grasshoppers this summer have overwhelmed the ability of the states to control them by normal means.

Officials of the affected states are moving quickly to control the infestation, which has become apparent only recently, by mounting intensive aerial pesticide-spraying efforts. The crisis has led some state officials to urge the Environmental Protection Agency to relax the rules and allow the temporary use of several extremely potent grasshopper pesticides the EPA banned four years ago as dangerous to humans. But EPA officials say the crisis can be fought effectively without using these particular pesticides. We think they're right. There are over 20 other grasshopper pesticides available, and the EPA is advising state officials on their use. Those pesticides have been effective in the past; with proper, quick application, they should be so now. At the least, state officials should give these safe pesticides a chance to work. The point is to eliminate a present danger, not to create a new one.