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Cluster flies: What you need to know

Cluster flies: What you need to know

About cluster flies:

Cluster flies, or ‘Pollenia Rudis’ are known as field flies. They lay eggs in soil and the larvae burrow into earthworms where they pupate. Several thousand flies will cluster together to form the infestation, hence their name. They are often slow moving in the hibernation season as they are going into stasis. However, when they come out of hibernation they will buzz around with a lot more energy. As research shows, there are eight species found in Britain, and thirty-one in Europe.


How to identify if you have and infestation:

As temperatures decrease in the Autumn, the flies start to seek shelter in the smaller areas of buildings hibernating in large numbers over the winter. The favoured area for flies to hibernate is usually a properties roof or loft space. People who live in the countryside are more prone to be plagued by Clustering Flies, this is due to being surrounded by large areas of grazing land or lawn, perfect conditions for flies to breed and lay eggs in undisturbed soil. Flies will normally infest the highest and warmest point available in the building, often the top floor of offices or loft spaces in residential homes. The flies can be attracted to light, this can lead them onto other floors in the property, much to the dismay of the resident/s.

While cluster flies are a pest, they pose no risk to human health with their presence never evidence for poor hygiene, simply bad luck and proximity to undisturbed areas of soil. Although they cause no harm to humans they are deemed a nuisance pest, due to the sheer volume of flies which can enter a property throughout the autumnal months. Clustering flies can often leave tiny dark coloured sports of excrement on walls and windows, which is not the most attractive sight and can be difficult to clean. If the flies die in inaccessible areas such as wall voids or false ceilings, they can attract other pests such as larder beetles. Any discovery of a large number of dead flies in a compact area is a sign that you have, or have had, an infestation of cluster flies.

How to treat an infestation:

If you think you have an infestation, we would recommend firstly identifying how large the infestation is. Once you know how large it is, we would recommend purchasing one of our two kits which can be found on our website If you are not wanting to purchase a full kit, we sell the items separately. If you are unsure about your infestation or would like some additional information, we can be contacted on 0114 2582407 and will be more than happy to give you some friendly advice! Alternatively, you can email us at and one of our advisors will be more than happy to help.