Chlorfluazuron and diflubenzuron effect were biologicaly and biochemicaly were studied by treated Agrotis ipsilon at early stage 2^nd instar larvae with two concentrations to show the stages diformities and changes in chitinase and phenoloxidase activities at three time intervals. The chitinase activity showed increase at 48h compared with 24h and 72h. Else, significant differences between the three times of treatment were observed in treated and control larvae. For illustration the mean of chitinase activities of chlorfluazuron LC₃₀ treatment were (333.3±7.0, 319.6±2.4 and 282.6±3.1ug NAGA/ min/g.b.wt. for 24, 48 and 72 h were noted. Phenoloxidase enzymatic activity after 72 hrs revealed significant decline at higher concentration. After 24 hrs of treatment, the highest phenoloxidase activity was with chlorfluazuron (170 ±4.58 O.D. units/ min/g.b.wt.) and followed by drastic decline at higher concentrations and exposure period (91.6±0.99 O.D. units/ min/g.b.wt.). The percentage of phenoloxidase activity compared with the control shows varied from each other according to larvae exposure period. The activity at the three different time intervals show increase at 48h in compared with 24h and 72h. The higher percentage comparing with control of phenoloxidase activity and the lowest were 83.58 to –5.4 %for chlorfluazuron at42 h, of LC₃₀ and chlorfluazuron at 24h, of LC₅₀. The biological results showed that the two compounds induced morphological abnormalities of all life stages of A.ipsilon, increase larval and pupal duration and decrease fecundity and fertility.