Adults live harmlessly out of doors in summer but may enter buildings (usually roof spaces and lofts but also through windows into rooms) in autumn to hibernate, sometimes in vast numbers. Other unrelated species may also cluster.
Eggs-laid in damp soil, rotting vegetation. Hatch in about a week.
Larvae – soon after emergence seek out and parasitise earthworms which are eventually killed. Development several weeks.
Pupae – in soil
Adults – 6 mm long, blackish with fine golden hairs on thorax (sometimes rubbed off). Often 2 generations per year.
The adult female lays eggs loosely on and around damp soil and beneath dead and rotting leaves. After about a week the larvae hatch from the eggs and actively seek earthworms to which they cling and then bore through the body wall. The conventionally-shaped fly maggots develop inside the earthworm. Later instar larvae have been observed to push their hind ends back through the earthworm body wall to allow their breathing spiracles to gain access to the free air. At or near the death of the earthworm the larva bores its way out again and pupates in the soil.
May be severe nuisance if large numbers of adults enter inhabited parts of buildings. Some buildings infested each autumn year after year.
Control of Cluster Fly
UPC has dealt with many cluster fly calls over several years and have always given the correct solution to each problem. It is usually a combination of an initial knockdown of Cluster Fly followed by a regular level of control by utilising specialist insect units. The fly control units are very specialist and the wrong advice could result in Health and Safety issues. It is therefore essential that only the correct solution provided by experts is given.