The efficacy of some bio-rational insecticides against tea looper complex, Hyposidra spp. was evaluated at two different locations of Dooars tea plantations, West Bengal. The results indicated that all the insecticides were effective in reducing the looper population to a significant level. However, in comparison to other insecticides, neem based insecticides could not give the desired level of

control. Among the different treatments, diflubenzuron 25 WP @ 700g/ha caused maximum reduction of loopers over control in both the sprayings at both the locations [Location I: 66.91% and 65.54% reduction of loopers at 7 days after 1st and 2nd spraying respectively) and Location II: 68% and 50.85% reduction of loopers at 7 days after 1st and 2nd spraying respectively)] and appeared to be the best treatment against loopers. Bt-k @ 1000 mL/ha was the next best treatment for suppressing looper population at 7 days after 1st spraying (64.44% and 67.81% reduction of loopers at Location I and II respectively) which was at par with recommended insecticide deltamethrin 2.8 EC @ 200 mL/ha (65.14% and 62.16% reduction of loopers at Location I and II respectively). However, in 2nd spraying, its efficacy was declined. Both the doses of Neem based insecticides recorded 31-49% reduction of loopers after 1st spraying but this was reduced only to 9-17% after 2nd spraying, Thus, in consideration of the performance of the insecticides, diflubenzuron @700 g/ha and Bt-k @ 1000 mL/ha could be included in the IPM package of looper.