Hi we have just arrived back at our house to a carpet of dead flies, I know we are in the country, but how do you minimise this? We had quite a few in the house, but this was loads all by the window areas? Any suggestions please


You're probably experiencing cluster flies.

Below is some info. Bombs or aerosols are not very effective as they have little or no residual effect. Sealing your house is the most effective but usually not possible.

Hope it helps!

Rob, Applicateur3d


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.


Egg - larva - pupa - adult.

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.


May be severe nuisance if large numbers of adults enter inhabited parts of buildings. Some buildings infested each autumn year after year.


Very difficult. Control of pre-adult stages not possible. Sealing entry points difficult. Vacuum cleaner to remove adults. Residual sprays or knockdown space sprays. Do not treat if possibility that bats are present in roof space. (Consult the relevant Statutory Nature Conservation Authority).

Distribution and Habitat

Found commonly throughout Europe and the UK. The common name refers to its habit of clustering and hibernating in numbers in buildings.


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 to the death of the Earthworm the larva bores its way out again and pupates in the soil.

Since this is a free-living "field" insect, the life cycle is very dependent on weather conditions. In Britain it seems that two generations per year are common and in hot summers up to four generations per year might be possible.

The adult flies, resplendent with their thorax clothed in golden hairs (which often rub off), feed on the nectar of garden and wild flowers.


During the summer and early autumn these flies are of no consequence. As the season cools they seek shelter in nooks and crannies in houses and other buildings. As temperatures drop they search for more protection and frequently form vast clustering masses in roof spaces and lofts. It has often been observed that the same house or building in a row of similar buildings will be chosen year after year.

Such large aggregations of flies do produce a rather sickly smell and, if warmed-up accidentally or artificially during their hibernation, may emerge rather lazily and create some consternation among people using the building. This has occurred commonly in church halls, domestic bedrooms and has even been recorded as a problem of fly-contaminated switch-gear in heated automatic telephone exchanges.

I had a discussion up a couple of weeks ago, in our case they were alive though. It took a whole lot of solutions like the nasty tapes (still have one up), continually cleaning (vacuum cleaner, wiping down, using non-toxic substances because of children, cats and dogs) having a fly catcher plant, no food or anything they might feed off in any sense left out. Search back for the post, see the advice I was given and hope there is an answer from somebody there already. Best of luck!