Chemical Control of Clover Leaf Weevil Larvae1

Abstract

Larvae of the clover leaf weevil ( Hypera punctata (F.)) were n serious pest of legumes in Southwest Kentucky during the spring of 1956. The usually prevalent fungus disease of this insect did not give satisfactory control. Field tests in combination with laboratory studies indicated that the larvae were relatively difficult to kill within a short time with economically feasible dosages of various insecticides. However, aldrin, Chlorthion, endrin, heptachlor, lindane, and toxaphene, all applied as emulsions, caused a high per cent of moribund individuals. These moribund larvae did little feeding and most of them were not able to complete development. Such larvae were commonly found in open spaces away from the host plant, and their numbers were reduced, presumably by predators. Diazinon and methoxychlor emulsions apparently had little effect on the larvae. The treatment with malathion emulsion gave the highest mortality of larvae soon after application but more larvae survived in this treatment than in some of the other treatments when the insects were held in laboratory cultures for several weeks. Granulated formulations of aldrin and heptachlor were far inferior to emulsions of the same materials used at comparable levels.