The adult cluster fly is around 10mm in length. They have one set of wings that are transparent, but show a distinct vein pattern. The thorax, which is the middle section that the wings are attached to, have distinctive grey/olive coloured stripes and are covered in fine golden hairs. The abdomen (or the main body) is grey in colour and has a chequer-board type pattern.
Cluster fly adults emerge from the ground in late summer/early autumn. They travel in large groups to find somewhere to hibernate, and often settle for a roof void. It is because of this that they are sometimes known as ‘attic flies’. A large number of flies flying around the property, or dead flies on window sills, will be a good indication that a swarm has taken up residence in your property.
Cluster flies present no significant risk to health, but can be a source of nuisance. Their presence should not be taken as a sign of poor hygiene, as they are merely seeking a suitably warm place to hibernate. If they are not dealt with, it is not unusual for them to return to the same property every year.
If you think you have cluster flies in your property, Arun District Council is able to help. We offer a prompt and professional treatment, and may be able to offer advice on future prevention. All services are chargeable, and the charge will cover you until the treatment is complete, with no hidden extras. Please call Arun Direct on 01903 737755 to arrange an appointment. Please note, the fee will be payable at the time of booking, so please have your card details ready. All payments are non-refundable.
We will attend your premises on the agreed date. Our Pest Control Officer will survey your property and treat as appropriate. An insecticidal spray is misted into the affected area via an ultra low volume machine. Windows are also treated with a water-based residual insecticide. Treatment for flies outside is a waste of time as environmental factors such as wind and rain will render the product useless. Sometimes a follow up visit may be necessary, but this will be arranged on a case by case basis.
Cluster flies are strictly parasitic on the earthworm. Females lay their eggs in the soil near earthworm burrows. The egg hatches and the maggots then infest the worm, eating it from the inside out. It pupates, and emerges from the ground as a fly. In order to break out of the pupae and reach fresh air, the fly inflates and deflates a sack on its head, called a ptillum. Resting when they reach the surface, the fly gradually unrolls its wings and dries itself out before moving away. They are sluggish fliers. Sometimes the flies may appear to be two different sizes, but this is not two generations, it is due to a lack of food in the larval stages. Cluster flies get their name from their hibernating habits, as they always swarm in large groups.