Cluster Flies - PEST UK

Providing pest control services in Berkshire, Buckinghamshire, Essex, Hampshire, Hertfordshire, Kent, London, Middlesex, Northamptonshire, Oxfordshire, Surrey, West Midlands, West Sussex, Wiltshire. Est. 1985.

Cluster Flies

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Cluster Flies

Cluster flies are a common problem for home owners this time of year. You may notice dead or dying flies or live flies around windows. You may even see some sunning themselves on outside walls. In autumn cluster flies hibernate in large groups over the winter and reemerge in the spring to lay eggs. Once a location has been chosen as a nesting site genetic memory seems to pass on the location to the next generation.

There are 3 types of cluster fly. The most common type is parasitic on earthworms, the other 2 types are the Autumn Fly, and the Green Cluster Fly, both of these breed in cow dung. All 3 species lead solitary lives except when they gather in the autumn to hibernate.

Before moving into their chosen hibernation place they will collect on the outside of buildings on sunny walls. Before finding their way inside to form clusters of many thousands in locations such as roof spaces, under tiles, window frames and in window sash boxes. They are not a health hazard and are only coming into the building to hibernate, not to breed or feed.


We will treat the infested and surrounding areas with one (or all) of the following insecticide sprays: Effect Microtech CS’* which contains Permethrin, HSE Number 6287, made by Sorex or Permost Uni, HSE Number 6399 which contains Permethrin & Tetramethrin & made by Hockley International or K-Othrine WG250, HSE Number 5390 which contains deltamethrin 25%. These insecticides are the most modern insecticide available. A smoke generator may be used, this is called a Coopex Smoke containing Permethrin. The type of insecticide used will depend on individual circumstances and be decided by the technician on arrival.

All these insecticides are biodegradable, almost odourless, non-tainting & do not corrode or stain. They are not highly toxic towards mammals but are extremely so to all forms of crawling and flying public health pests. All the resting places will be treated.Cluster flies


PESTUK are full members of the BPCA, the governing body for pest control in the UK. Using a BPCA member company ensures you have a qualified, fully insured company treating your pest problem.

PESTUK have offices in Oxford, Guildford, Enfield, Shepperton, Wantage, St. Albans, Salisbury, St Albans and Enfield.

Call us on 0330 100 2811 to book an appointment regarding Cluster flies or any other pest problem you may have.


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