Abstract: The willow gall midge,Rhabdophaga sp.is the most injurious insects of the willow (Salix sp.)in Kiangsu Province.It causes considerable damage to the trunk of the willow annually.In order to hold this species in check,a study was carried out during 1977.The main results obtained from this study are summarized as follows. The willow gall midge as in generation a year in Kiangsu Province.It overwinters in the larvae stage on the willow trunk bark.The fullgrown larvae pupate near surface of galls in early March of the next year.The adults emerge in late March to late April and lay eggs in the emerge holes of the gall,at the base of adventitious buds and the crevices of the trunk bark.Each female lays about 150 egges.The larvae at first injure the bark and then bore into the trunk and last to add to building galls on the willow trunk. Preliminary experiments showed that the following control measures were effective: 1. In mide and late March to brush the gall of the trunk with Fuel oil and BHC mixture at a concentration of 10:1 was good to kill the pupae and fullgrown larvae. 2. In late April and late May to inject 40% omethoate or 40% Rogol emulsion into the hole,made with a chisel or to scratch and brush the trunk with the same emulsion,was good to kill the larvae in galls.