Inclusions in the Fat Body of the Alfalfa Leafcutter Bee, Megachile rotundata1

Numerous white lesions in the fat body of the alfalfa leafcutter bee, M. rotundata (F.), are composed of proteins, DNA and RNA. Electron micrographs indicate that the lesions are groups of inclusion bodies, 4—10 µ in diameter. Larvae containing high concentrations of lesions have a higher mortality rate. The relationship with mortality structure, and chemical components suggests that that the lesions may be viral in origin.