The Biological Background of Locust Control

Abstract

There is no single species properly named locust, for intensely migra­ tory and swarming species, like the desert locust of the Bible, shade off into sedentary and nonswarming grasshoppers, some of which cause local damage. Few generalizations are applicable to such varied species. Not one has yet been deliberately brought under complete control by ecological methods; but the Rocky Mountain locust [Melanoplus spretus (Walsh)] has been ac­ cidentally discouraged by man during the colonization of the North Ameri­ can prairies and may be extinct (10); on the other hand Locusta and the Moroccan locust [Dociostaurus maroccanus (Thunberg)] have been en­ couraged by man (131). Although ecological methods of control are being sought (4, 26, 46, 76), at present all effective and economical control de­ pends on chemical insecticides; it is unlikely that ecological control will soon, everywhere, oust chemical control, so the biological background of the latter is worthy of consideration and improvement in its own right. Both the strategy and the tactics of chemical attack depend on the biology of the species concerned; they also depend on finance and politics.