Abstract: 1．AII four inseotlcldes are practically non-toxic to the eggs of elm leaf beetle,indicating that they we not ovicides. The reduction of the mlulber of insects howevet is due to the residual toxic action of these chemicals on the newly-hatched larvae. 2．All four insecticides kill the larvae．Pupae anIt adultq effectively．For tile larvae.the mature larvae are more rest stant than the young ones and the newly—hatched larvae are most sensitive to the toxic action of these chemicals. 3. For the comparative toxicity of the four insectlcides,they are almost equal toward the adults,with gammexane slightlymore preferable. For larvae, DDT is in no way inferior to Gammexane, and both are more effective than Chlordan and Toxaphene; Chlordan being the least effective. For pupae, DDT, Gammexana and Toxaphene are about equal and aer all better than Chlordan. The order of decreasing toxicity in general is: DDT=Gammexane>Toxaphene>Chlordan