Do you have cluster flies?

31 October 2018

Cluster flies migrate into roof spaces and subsequently into living quarters in the autumn where they become a nuisance pest to inhabitants. They are not generally considered to be carriers of disease although having several hundred flies dying in the bedroom is not considered very hygienic.


Adults are up to 10mm in length with a wingspan of up to 20mm. The thorax is a dark grey / olive in colour and covered in golden hairs. The abdomen has a chequered pattern. When at rest, the wings usually overlap each other over the abdomen.


Flies enter buildings in autumn, via gaps in window frames (Old sash windows tend to be a good harbourage where flies will hide in the sash runs and pulley holes), and on roofs. Problems usually arise when heating is turned on and flies enter rooms through gaps under skirting boards, holes in the ceiling etc. As they are parasitic to earth worms, buildings surrounded by large expanses of grassland tend to suffer more than town houses. It is not uncommon for several thousand flies to infest roof voids or unused attic rooms.

Life Cycle

Adult female flies lay eggs in the entrances to earthworm burrows. Hatching larvae enter under the skin of the worm when it emerges and feed on the worm until they are ready to pupate. They then leave to worm to pupate in the soil before emerging as an adult.

Control Methods

ULV treatment or ‘Misting’ and insecticidal smoke bomb treatment are particularly effective at knocking down flies in roof spaces. Note: If using smoke bombs it is advisable to contact the local fire brigade to inform them of your intentions, in order to avoid a false call-out. It is always important to check for bat habitation in roof spaces as this can restrict treatment due to protection laws. Windows can be treated with residual insecticides. Locating and proofing entry holes in rooms may also alleviate the problem.

For further advice contact the Abate team on 0800 9809767

Cluster Flies Norfolk  Cluster Flies Norfolk  Cluster Flies Norfolk  Cluster Flies Norfolk



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