inefficiency of non- chemical control measures in its control, farmers rely only on insecticide applications. Because of insistence in recommending specified insecticides for a prolonged period of time, the susceptibility of the pest to on two the recommended insecticides: endosulfon and phosalon was examined. Bioassay tests were carried out through topical application. The results indicated that LD50s for endosulfon and phosalon were 18.85 and 28.46 ig!insect respectively. A commonly used dose of these insecticides in the field is about 2 lit/ha; this dose being equal to 4000 ppm, based on using 500 liters of insecticide solution per hectare. Comparisons made between recommended doses and estimated LD50s showed that LD50s were 13.46 and 20.3 times the recommended doses for endosulfon and phosalon respectively. Based on these results recommended insecticides for CPB can not effectively control the pest and therefore must be eliminated from the recommendation lists in Hamedan province.
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