Studies of aleochara tristis (coleoptera: staphylinidae), a natural enemy of the face fly.

Abstract

In 1961 the staphylinid Aleochara tristis Gravenhorst was found for the first time parasitizing the face fly, Musca autumnalis De Geer, in France. Life-history studies were made of the beetle before its recent introduction into the United States. It is a multivoltine species and the adult may live 1 year or more. Under laboratory conditions (uncontrolled room temperature and humidity), the egg stage lasts 5–6 days, the larval stage from 6 to 14 days and the pupal stage an average of 21 days. The newly hatched larva enters a face fly puparium, develops within as a parasite of the pupa, and emerges as an adult. Occasionally the fly is able to escape parasitism by closing off the larval entrance hole before the larva has penetrated. Multiple larval attack overcomes this defense mechanism, and the fly succumbs. However, only one of the attacking beetle larvae completes its development. The adult beetle is predacious on larvae of several species of flies occurring in cow dung, but the larva appears to be more restricted in its host range. Initial tests also indicate that older puparia are more susceptible to larval attack than others. The adult beetle overwinters in the dung in the field. Since the farmers in France gather the dung for compost, the effectiveness of this beetle there may be greatly reduced by the annual depletion of the overwintering population.