Cluster flies are about 7 mm in length and can be recognised by the distincivet lines they have behind the head. They also have short golden-coloured hairs on their thorax, and irregular light and dark grey areas on the abdomen. Unlike blow flies, cluster flies are typically slow-moving. Cluster flies are a nuisance and a common pest, especially in rural areas where a property is surrounded by green fields. This is because cluster flies are a parasite of earth worms. They are known to infest properties and a property’s roof space in the Autumn months as the temperature begins to drop. 

Locating if you have a cluster fly infestation is not difficult. If they are hibernating in your loft space, they will often erratically fly into you when you are doing an inspection for them, as they are very active under lighting conditions. If the cluster flies are hiberating in the living areas of your property, you will often find them hiding behind curtains, doors and the backs of furniture, where they like to hide to avoid being disturbed. 

As the temperatures begin to increase in Spring, cluster flies will wake from their dormative state known as diapause, and they will fly towards a natural light source in an attempt to fly back outside to breed. If you have a cluster fly infestation in your loft space, cluster flies can often find their way into your property’s living area, typically throw a light fitting’s ceiling rose, or other gaps between the ceiling. When they do, you will often find them around windows, attempting to get out.