An issue with flies isn’t always caused by house flies
Often in rural areas, flies can be seen inside even when the doors and windows are shut. These flies are not be confused with house flies seen frequently in the Summer months; these ones are much slower and cluster around windows and walls – hence the name Cluster Flies.
They tend to enter properties as it starts getting cooler from September onwards and can be seen even during the winter months as they invade in order to hibernate in the warmer areas.
Preferable hibernating areas include loft spaces and anywhere close to a window as they will usually use the gaps in roof tiles and the windows to gain access. Most people notice an infestation when they start seeping through spotlights in bathrooms from the loft or when they go into the attic to bring down decorations for Christmas.
The main way to tell a cluster fly from a housefly is the speed at which they move. They buzz around very slowly and usually in groups. Another way to distinguish a cluster fly is by their wings; these overlap when the fly lands on a surface.