cluster flies

Cluster flies, common problem in lofts and can  hibernate  in lofts and in window frames perimeter of buildings.

Knight pest control can offer a fast treatment to gain control of cluster flies in your home or business, so call today for a fast response.

These are dark greyish flies about 8mm long with yellowish hairs on the back and with overlapping wings. In autumn they congregate in large numbers in upper rooms or roof spaces of houses to hibernate. A mass of cluster flies has a characteristic smell. They are sluggish in flight and are a nuisance in the house.
During the summer months these flies live and breed in fields and are not a problem. They are parasitic on earthworms and their larvae live in the soil, emerging as adults at the end of summer. In the autumn under natural conditions they would hibernate in dry sheltered areas such as under loose bark or in hollow trees. The survivors of the winter would then emerge the following spring to return to the grassy fields to continue their life cycle. However, with houses close to open spaces and fields it is quite common in the autumn for these flies to congregate in large numbers on the outside of buildings, especially on sunny, south-east facing, light-coloured walls. As the afternoon temperatures begin to fall they tend to crawl into crevices for shelter, sometimes through window frames, but mainly under the eaves/fascia boards into the roof space.
The following days they may emerge and sun themselves but as autumn moves on and temperatures drop they finally remain inside until the process is reversed the following spring. The big problem is that they tend to invade in large numbers. Fitting fly-screens is of little use against this specie of fly as it prefers to squeeze into small cracks around tiles, window frames etc., hundreds of flies in a loft are a big nuisance. The flies tend to return to the same property year after year. Even if there are similar buildings nearby, they may not be affected. It is not known why one building is preferred, it may be that the flies are attracted to lighter coloured buildings, sunnier spots, or use pheromones to locate old roosts, it is certainly no suggestion that it is due to poor hygiene.
What Can Be Done?
There is very little that you can do to stop the flies getting in. Making sure that gaps around window frames are re-pointed and sealing obvious entry points can offer limited help, but it is not really possible to stop a fly getting into a loft and if one fly can get in, so can the hundreds of others. The good news is that although you may be unfortunate and have invasions of cluster flies every year, control is fairly easy. Using an ordinary aerosol fly spray in the loft will kill all the cluster flies it hits, but will not penetrate into the cracks where flies may be hibernating.
knight pest control can carry out an insecticide ULV treatment, ulv  treatment is a very effective way of killing all the cluster flies due to its flushing agent, which is capable of penetrating all gaps, cracks and crevices, flushing the flies out into the open, it will kill all the flies that are present but won’t stop the next generation, over time you can brake the cycle.
for a cluster flies treatment a survey of the loft area is required to identify of Bats are present.
National Bat Helpline
0345 1300 228

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