EFFICACY OF INSECTICIDES AGAINST STETHOPACHYS FORMOSA BALY (COLEOPTERA, CHRYSOMELIDAE), A PEST OF ORCHIDS IN EASTERN AUSTRALIA

Experiments were carried out to determine the efficacy of insecticides for control of the orchid beetle Stethopachys formosa Baly on the ora nge crucifix orchid Epidendrum x obrienianum as plant host. Bendiocarb 0.4 g L(-1), carbaryl 1.0 g L(-1), methidathion 0.5 g L(-1), and meth iocarb 1.5 g L(-1), were the most effective spray treatments, rapidly killing adults. Dimethoate 0.3 g L(-1) and maldison 0.5 g L(-1) were l ess effective, whilst diazinon 1.32 g L(-1) fluvalinate 0.96 g L(-1), pyrethrum 0.78 g L(-1) and trichlorfon 1.25 g L(-1) were ineffective. Bendiocarb, carbaryl, diazinon, fluvalinate and methidathion applied t o eggs all prevented maturation of larvae. Carbaryl 1 g L(-1) effectiv ely controlled field infestations.