Cluster Flies Pest Control Products from DIY Pest Control Cluster Fly (Pollenia rudis) The Cluster fly is about 6mm in length with a wing span of around 10mm.Mottled grey/brown in colour with yellow-gold hairs covering the thorax (mid section), by which they can be recognised, and a bristly abdomen. They are slightly larger than a house fly. As the name implies, these flies can cause a nuisance through their habit of "clustering" together in their thousands, usually in roof spaces. They are a particular nuisance in Autumn when they are looking for a roof void to spend the winter, and again in Spring when they start to emerge as the weather turns warmer. Often these flies will migrate from their overwintering into rooms below or into attics that may have been converted into living accommodation. Cluster flies will very often return to the same roof spaces year after year, usually to houses on a hill with countryside around or nearby, but not exclusively. Other Species The Autumn Fly (Musca autumnalis) The female autumn fly lays its stalked eggs on animal dung in fields and the larvae develop within the dung and pupate in the surrounding soil. The adult flies tend to feed on body secretions of animals in the fields. Their hibernating behaviour is very similar to the cluster fly and they frequently form mixed populations inside suitable buildings. Green Cluster Fly (Dasyphora cyanella) In the same family as the quite common greenbottle and very similar in appearance. This is another species where the larvae develop within the dung on which the adult female has laid her eggs. As with all outdoor insects, the life cycle is very dependant on weather conditions; from egg to adult may take anything from 6 to 10 weeks, and the adults are usually active from early summer right through to the onset of cold late autumn weather. The seeking of hibernation sites is similar to the autumn fly and is frequently a member of mixed swarms in roof spaces.

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