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Cluster Flies

Cluster flies are common . The adult is about 6mm long, and has distinctive golden hairs on the thorax (chest) area. The flies live outdoors, and the adults feed on nectar from flowers. The fly lays eggs in damp soil and rotting leaves. When the eggs hatch, the larvae hunt and destroy earthworms, before hatching into an adult fly. This life cycle is part of natures normal unseen jungle warfare that goes on in gardens, and the cluster fly lives in balance with the rest of the garden wildlife. From the human point of view the fly is harmless. They do not breed indoors, they are not thought to carry any diseases, and their presence is not a sign of poor hygiene. There is no need, and in any case it is not practicable, to try to control the flies outdoors or to control their breeding areas.

SO WHAT'S THE PROBLEM ?

In the autumn, the flies look for shelter and will hibernate over the winter. The best shelter they can find is in lofts, or in big buildings like church halls. Sometimes they will invade the living space of house.

The problem is that they tend to invade in large numbers. A single fly is no problem, hundreds of flies in a loft is a big nuisance.

Another problem is that although there may be an invasion of flies in the autumn, this could go unnoticed. If the loft or spare room is warmed up during the winter, the flies may emerge and cause a sudden problem

The other bad news is that 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, but it is certainly no suggestion that it is due to poor hygiene

As well as the Cluster fly, there are a four other species which are similar, so it is possible to have mixed populations of flies causing the problem

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 repointed, and sealing obvious entry points can 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 flyspray in the loft will kill all the cluster flies it hits, but will not penetrate into the cracks where flies may be hibernating.

For small infestations, if you do not want to use insecticides, a vacuum cleaner can be effective in sucking up large numbers of flies. You need to empty the cleaner out of doors into a sealed bag when you are finished. Like a flyspray, this will only deal with the flies you see - it will not control any that are hidden and hibernating

CALLING IN PROFESSIONAL HELP

A pest control technician has access to more effective insecticides and equipment. We will carry out an inspection of the property and suggest the best method of control. The methods we might use are

smoke generators, which will give a quick knock down of all flying insects, and some control of those that are not deeply hidden in cracks, but will have little long term effect using a powered fog generator. This can clear large buildings very quickly and will penetrate into hiding spaces. This equipment allows us to do the job without having to use expensive scaffolding to reach roof spaces in big buildings like churches where it is easy to reach all parts of the building we can use a low pressure spray. This will give a quick knock down, and will continue to kill any emerging flies for several months.

CAUTION - Are there bats in your loft ?

In old houses or big buildings, cluster flies may be in a loft where there are also bats. It is illegal to use insecticide if there is any possibility that it might come into contact with bats. If this is the case, we will discuss with you the available options for control. Whatever we do, both we as the pest control contractor, and you as the occupier, have a legal duty ensure that the bats come to no harm