With the increasing uses of biological control methods, knowing the physiological and immunological effects of these insecticides on insects is essential for them to be used safely in agricultural areas. The aim of the study is to determine the effects of pyriproxyfen and Bacillus thuringiensis subsp. kurstaki individually and as a mixture on malondialdehyde levels (MDA), glutathione-s-transferase, acetylcholinesterase, cytochrome P450 enzyme activities in hemolymph, midgut, and fat body and total (THC) and differential hemocyte counts (DHC) of fifth instar larvae of Galleria mellonella (L., 1758) (Lepidoptera: Pyralidae) 24, 48 and 72 h after exposure under laboratory conditions (30 ± 1ºC, 65 ± 5% RH). The study was conducted in the Animal Physiology Research Laboratory of the Department of Biology, Faculty of Science and Letter, University of Çukurova between 2016-2018. Effects of these insecticides on antioxidant, detoxification enzyme activities and MDA levels were changed depends on exposure time and the differences of tissues. THC decreased after 24 h, whereas it had increased after 48 and 72 h. DHC induced depends on exposure time and applied insecticide. This study revealed that pyriproxyfen and B. thuringiensis applications caused biochemical, physiological reactions and effected the immune defense system of larvae by the alterations in hemocyte counts.