Fatal Aspergillus flavus infection of Desert Locust at Field Station for Investigations on Locusts, Bikaner, India, has been described. The infection appeared in the form of pinkish to brownish black patches with hardening of the affected regions, paralysis and twichings of the legs. The fungus was demonstrated in the lesions and was isolated from the diseased parts as well as from the air, floor and walls of the breeding cabin. The cool and humid conditions of the cabin favoured growth of the fungus and the air blasts helped in dissemination of its spores in the air which predisposed the disease. The infection appeared exogenous with the fungus gaining assess through surface and invading the deeper tissues. It has often been observed at the Field Station for Investigation, on Locusts, Bikaner, India, that the mortility rate of Desert Locust (Schistocerca gregaria Forst) at times increased to a frustrating level preventing the building of a good laboratory stock (5). All the diseased and dying insects showed similar features. Sporadic deaths occurred throughout the year and were preceeded by similar signs and symptoms. On 12th May 1975 following a two day dust storm about 40% of the insects in a breeding cabin developed these features and ultimately died. This paper describes investigations under taken at our end to study aetiopathogenesis of this disease.