Cluster Fly - female

Description:

Cluster Flies are slightly larger than the common house fly and have golden-yellow hairs on the thorax, which can give the appearance of a golden sheen. Females deposit their eggs on soil. Once the eggs hatch, the larvae burrow into earthworms on which they feed.

Habitat:

Cluster flies are thought to be native to Europe and may have found their way to North America in the ballast of ships containing soil and the cluster fly host, earthworms. Adults over-winter in such locations as hedge rows; under the bark of dead and dying trees; in the crevices of south-facing cliffs and rock faces; and within the cracks, crevices and voids in sheds, garages, barns, houses and other man-made structures.

Notes:

These over-wintering flies have suddenly emerged everywhere in my woodland garden. It leads me to wonder if I will have any earthworms left for the growing season... They mostly have been observed drinking sap from freshly cut logs.