Cluster Fly Fumigation Cambridge

People often ask us to fumigate a loft for cluster flies. What they want is for the sluggish flies at the upstairs windows to stop, and this guide explains how that is done, what it can and cannot achieve, and why the same house can attract them again the following autumn.

For other flies, such as house flies around bins or tiny flies at the sink, the fly control service page covers the wider service.

How to Recognise Cluster Flies

Cluster flies look a little like house flies but behave differently. The clues are mostly in when and where you see them.

• Slightly larger than a house fly, dark, with fine golden hairs on the body that you can sometimes see in good light.
• Wings that fold over one another across the back when the fly is resting.
• Slow and clumsy, often buzzing weakly at a window or lying on the sill.
• Seen in autumn, winter and early spring, often on a sunny day, in lofts and top-floor rooms.
• Found in groups in the corners of windows, in the roof space and around the loft hatch.

If large, noisy flies appear suddenly with an unpleasant smell, that points to something dead in the building instead, which is a different job.

Why They Choose Your Loft

Cluster fly larvae develop outdoors in soil, where they feed on earthworms. That is why they are associated with homes next to fields, paddocks, parks and large lawns, including on the edges of Cambridge and in the surrounding villages.

In late summer and autumn the adults look for somewhere sheltered to spend the winter. Roof spaces, gaps around window frames and the voids behind fascias suit them well, and walls that catch the afternoon sun seem to attract them in particular. They get in through very small gaps and settle in large numbers.

What a Cluster Fly Treatment Involves

The word fumigation is used loosely. What we do is treat the loft and the places the flies are gathering, so that the flies already sheltering there are killed and those moving around the roof space pick up the treatment. Upstairs rooms where they keep appearing can be treated as well.

• Confirming they are cluster flies, because the treatment for house flies or blow flies is different.
• Treating the roof space, concentrating on the areas where the flies cluster.
• Treating resting surfaces in affected rooms where appropriate.
• Telling you before the visit what will be used, where, when the loft and rooms can be used again, and what to do with pets. Follow those instructions.

Afterwards you will find dead flies in the loft and on windowsills for a while. Vacuum them up, because large numbers of dead flies can smell and attract other insects.

Cluster flies are a seasonal visitor to the roof, not a sign that anything is wrong with the house.

Price and the 14-Day Guarantee

Fly control is £180 fixed cost, with no call-out fee, and the price is confirmed before anything is booked. The fly control cost guide explains what the figure covers. Every treatment is guaranteed: if the problem comes back within 14 days of treatment, we return and re-treat free of charge.

Will They Come Back Next Year?

Quite possibly. The things that drew them to your roof, the nearby grassland, the sunny wall and the gaps they came through, are still there the following autumn. A treatment deals with the flies that are in the building now; it does not change where the house is.

Sealing gaps around window frames and fitting screens to windows you open can reduce the numbers, although sealing a whole roof against an insect this size is rarely realistic. If you are not sure what you have in the loft, a pest inspection is £120 fixed cost. For other loft visitors, see our guides on rats in the loft and squirrels in the loft.