Effects of a fungicide, Guazatine, designated SN 513 (9-aza, 1, 17 diguanidinoheptadecane triacetate, Keno Card AB, Stockholm, Sweden), on feeding of various insect species were investigated in the laboratory. The reduction in feeding of all species tested, except the southern green stink bug, Nezara viridula (L.), and the velvetbean caterpillar, Anticarsia gemmatalis Hübner, was significant, predictable, and directly related to the log 10% concentration. Insects listed in approximate order of most to least sensitive to SN 513 were the Mexican bean beetle adult, Epilachna varivestis Multan, Colorado potato beetle adult and Lana, Leptinotarsa decemlineata (Say), tobacco hornworm larva, Manduca sexta (L.), cabbage looper larva, Trichoplusia ni (Hübner), corn earworm larva, Heliothis zea (Baddie), diamondback moth larva, Plutella xylostella (L.), beet armyworm larva, Spodoptera exigua (Hübner), brown stink bug adult, Euschistus servus (Say), and soybean looper larva, Pseudoplusia incluclens (Walker).