Termites are economically important insects. They cause damage to furniture, household goods, timber and forest vegetation. Present study was designed to determine the effect of fungus isolates at six different exposure times on Coptotermes heimi (Wasmann), which is one of the major destructive termites of Pakistan. Fungal conidia were repellent to C. heimi. The workers of C. heimi were exposed to fungus for 60, 45, 30, 20, 15, 10 minutes and percentage mortality and consumptions were noted during eight days period. Results showed that workers of C. heimi responded effectively to different exposure time. Percentage mortality in 10, 15, 20, 30, 45, 60 minutes exposure was 46.7%, 55.6%, 67.5%, 76%, 85.3%, 100%, respectively. And, control showed 0% mortality. There was marked reduction in consumption by termites subjected to different exposure time. Consumption in all groups was significantly lower than control.