The present study aimed to find out the histopathological change in the testis adult male insects Odontopus varicornis. The study on median lethal dose of phytopesticide Azadirachta indica was determined to be approximately 0.05 ppm for 48 hours. The male reproductive system of Odontopus varicornis is formed as a pair of testis, vas defence, seminal vesicles, the mature Odontopus varicornis has two nearly uniformly broad testis. The testis were flattened leaf-like structures with white connective tissues and layers of a peritoneal connective sheath. A common ejaculatory duct and then into aedeagus. The testis of treated insects showed the presence of a ruptured testicular follicle, disintegrated spermatocytes, pycnotic and necrotic spermatids. The toxicity impact of phytopesticide on Odontopus varicornis was appropriate to be comparatively higher than other insects.