Abstract
A fungus, identified as Aspergillus flavus (Deuteromycete: Hyphomycetes), was isolated from dead, field‐collected Vespula vulgaris larvae (Hymenoptera: Vespidae). After isolation and pure culturing, the fungus was inoculated onto field‐collected larvae of V. germanica and V. vulgaris. Disease symptoms developed in some larvae within 24 h, and eventual emergence among treated V. germanica larvae was only 0.8% compared to 52% in the untreated controls, and 1.3% compared to 40.9% for V. vulgaris. Although the fungus demonstrates the potential of inundative pathogens as control agents of social wasps, the production of human carcinogenic aflatoxins by most A. flavus strains is expected to restrain consideration of this fungus as a biological control agent.