Cluster Flies

At this time of year we always have lots of calls about fly problems. People report that they have flies in the windows and around the outside of the soffits and loft area.

These will often disappear for a few months and then reappear in spring causing the same problems. This pattern then continues year after year! The issue is cluster flies.

Cluster flies, as their name suggests, cluster together during the winter months and hibernate. They often choose our lofts and attic spaces to do this. They use the same hibernation sites year after year, bringing the young back with them and so the cycle continues.

The flies that you see in the windows at around this time of year are attempting to access the house. What often happens is that we get a cold evening, the flies think that it is time to hibernate and therefore enter the property. We then have a warm couple of days, they realise they are too early and then attempt to leave again, often getting trapped behind windows etc. These ‘false starts’ will happen several times during the autumn. The same thing then happens in spring. We have a couple of warm days early on, only for the weather to turn cold again. The flies leave thinking summer has begun, but then attempt to re-enter the house when they realise their mistake.

The flies we see in our windows are only a tiny proportion of the clustering population. They cluster in our lofts in their thousands. At AMS Pest Control, we advise that for complete control, the treatment is carried out during the winter. Treat them too early, or too late and the whole colony will not be in place. The numbers will replenish during the summer breeding and the same problem will be present the next year.

It is so often the case that people leave it until the spring to call us and then have to wait until the following winter for effective treatment.

AMS Pest Control covers all of Coventry and the Midlands so call us to get rid of this perennial problem.

It is also worth mentioning that harlequin ladybirds, an increasing issue in the UK, behave in a very similar manner. They cluster in our lofts in the thousands and can often be found on windows at this time of year. This non-native, invasive species can be treated in a similar way, so get in contact if you require any further information.