This study aimed to evaluate effect of LC50 of Croton tiglium oil and its nano-emulsion on the biochemical response of the larvae of the spiny bollworm, Earias insulana. Treatments elicited decreasing in total carbohydrate, Glutamic pyruvic transaminase (GPT) and trehalase in the larvae of E. insulana as compared with control. The level of total lipid increased with nano-emulsion of C. tiglium oil and decreased with C. tiglium oil in the larvae of the spiny bollworm. Two treatments decreased levels of total protein in the larvae of the spiny bollworm. Tested two compounds elicited decreasing in Glutamic pyruvic transaminase (GPT) in the larvae of E. insulana as compared with control. Application of the two compounds reduced glutamic oxaloacetic transaminase (GOT) levels in the larvae of E. insulana. Croton tiglium oil decreased invertase enzyme levels, while its nano emulsion increased its levels in the larvae of E. insulana. Treatments caused inhibition in trehalase levels in the larvae of E. insulana as compared with control. C. tiglium oil increased levels of lipase enzyme, but nano-emulsion of C. tiglium oil caused inhibition of its level in the larvae of E. insulana. The treatments decreased levels of protease enzyme in the larvae of the spiny bollworm as compared with control. The two compounds under study increased acetyl cholinesterase activities in the larvae of the spiny bollworm as compared with control.