Chemical Control Study of Soil Insects in High Mountain Li-shan

1. The most prevalent soil insects occurred in Li-Shan were cutworm Euxoa segetis Schif., some species of white grubs and wireworms. But Euxoa sagetis and white grubs were more harmful than wireworms. 2. These soil insect population of this region even the newly or old reclaimed slope land was heavier than terraced. However, there was on difference between the old and newly reclaimed slope land, but white grubs of old slope land was heavier than the newly ones. Moreover, the soil insect population of old reclaimed terrace was double more than newly reclaimed ones. Soil treatment of 1.0, 1.5 and 2ppm of aldrin wp or granular distributed on the soil surface and worked into soil as 15 cm immediately even one year later, was given perfect control and no significant difference among these treatments. 3. Before one week of transplanting cabbage seedlings, soil treated with aidrin wp or granular and worked into the soil as deep as 15 cm immediately for control cutworms was given good results, but in heavy population of cutworms, it had better 2 weeks before to treat the soil was more effective, or the aidrin dosage was increased to 1.5 or 2ppm. Otherwise, 14 days later of transplant might be replanted the missing plant or adding extra spray of 0.1% DDT concentration to protect these seedlings. 4. For protecting potato tuber against white grubs and wireworms 1 ppm of aidrin wp or granular was enough to give the perfect control