Common Cluster Fly

Distribution

This species is widely distributed throughout the United States, Canada, and Europe and is considered a pest species in structures. "P. rudis" can be found wherever their host earthworm, the "Allolobophora" genera, occurs. These earthworms are typically located in well-drained, silt-loam soil with grass cover. During the summer, "P. rudis" can be found in fields and open areas. It is only when there is a sudden drop in temperature that the cluster fly shifts to the interior of structures, holes in trees, loose bark, or other crevices and cavities.

Behavior

The behavior of the "P. rudis" fly varies with the annual seasons and conditions of the day. During the summer, on a sunny day these flies can be found without much trouble. When it is cold these flies tend to find somewhere warm and dry. They are mainly found in forest or wooded areas during the cold season. The flies tend to frequent dry areas because of their aristae antennae. The aristae are sensitive to minute temperature and pressure changes. During the winter, adult "P. rudis have a habit of overwintering. This ritual begins when the weather starts to get cold. The flies will inhabit the old tunnels created by past insects. They can also be found in old bird nests, under the bark of trees, or in homes. "P. rudis" will overwinter until spring, living off of its own fat.

Food

Earthworms are a major source of food for "Pollenia rudis". The main species of earthworm that these cluster flies infect are, Aporrectoda chlorotica,, "Lumbricus rubellus", and "Lumbricus terrestris". Immediately after the larvae hatch, they begin looking for worms. The first instar larvae eat their way through the integument section of the earthworm’s epidermis. While feeding, the "P. rudis" larvae leave the spiracles outside of the earthworm. Inside the earthworm, the larvae feed until they are ready to pupate. The adult "P. rudis" are, in most cases, herbivores. They feed on many types of organic matter. Plant sap, fruit, flowers and feces are common energy pathways for "P. rudis". "P. rudis" is also attracted to malt extract, acetyl acetate and the proteins in animal meat.