Abstract:Omphisa plagialis Wileman is an important insect pest of Catalpa bungei C.A.Meyer and causes severe damage to the growth of the young trees.The bionomics and control methods were studied in the laboratory and in the field from 1986—1990.It has two generations per year in Henan and overwinters as full grown larva in the branches and in the trunks.The peak period of eclosion of the second generation adult and hatching of the first generation larva (May) are the best period for chemical control.In this period, the control efficacy reaches 100% with 20% Fenvalerate(1:10000) or with 2.5% Decamethrin EC (1:5000); the plastochrone is 5—10 days (spray 3 and 4 times, respectively). Embedding 3% Carbofuran granules around the roots to control the larvae of 1—2 year young trees, the dosage is 25g per tree, the control effect is 97.87—98.10%.