Cluster Flies in Lofts This Autumn: Why You’re Seeing Them Now Around the Malvern Hills
As the days shorten and temperatures drop, many homeowners across Worcestershire, Herefordshire, and Gloucestershire notice an unexpected problem: dozens, sometimes hundreds, of slow-moving flies gathering in lofts, spare rooms, or window frames. These are cluster flies – a seasonal nuisance that returns each autumn. If you’re based in the Malvern Hills or surrounding towns and villages, here’s what you need to know about them – and how Malvern Pest Control can help.
What Are Cluster Flies?
Cluster flies (Pollenia species) are often mistaken for house flies, but they are slightly larger, darker, and move more sluggishly. Unlike house flies, they don’t breed indoors or feed on waste. Instead, they spend summer outdoors, laying eggs in the soil where their larvae parasitise earthworms. As autumn arrives, adult cluster flies seek warmth and shelter in buildings – particularly lofts, roof voids, and sunny window frames.
Why Do Cluster Flies Appear in Autumn?
Cluster flies are seasonal invaders. As temperatures fall, they group together in large numbers to hibernate. Older rural homes, farmhouses, and properties near open countryside are particularly prone, as the flies squeeze through tiny cracks, vents, and roof gaps to overwinter in safety.
Signs of a Cluster Fly Infestation
You may notice:
• Large numbers of sluggish flies on sunny windowsills or in lofts.
• Buzzing or crawling flies gathering in roof voids.
• A musty smell caused by large groups of flies.
The problem often reoccurs each year as the flies return to the same hiding places.
Are Cluster Flies Dangerous?
Cluster flies are considered more of a nuisance than a health hazard. They don’t spread disease like house flies, but in large numbers they can cause unpleasant odours, staining, and contamination of food preparation areas. They can also be distressing when emerging in spring as they attempt to leave the building.
How to Prevent Cluster Flies
While it’s impossible to completely prevent cluster flies in rural areas, some steps can reduce the risk:
• Seal cracks and gaps around windows, soffits, and vents.
• Fit mesh screens to roof and air vents.
• Check loft insulation and roof lining for holes.
• Keep windows closed on warm autumn afternoons when flies are most active.
Professional Cluster Fly Treatment in Worcestershire, Herefordshire & Gloucestershire
Once cluster flies gain access to your loft or roof void, DIY sprays usually won’t solve the problem. Professional treatments – including residual insecticides, ULV fogging, or smoke generators – are the most effective way to remove large infestations safely. At Malvern Pest Control, we use safe and proven methods tailored to your property, ensuring fast relief and long-term prevention strategies.
Why Choose Malvern Pest Control?
• Local, family-run business covering Worcestershire, Herefordshire, and Gloucestershire.
• Discreet, fast-response service with same-week appointments available.
• Fully trained and insured technicians using professional-grade treatments.
• Friendly advice on prevention to reduce repeat infestations year after year.
Book Your Cluster Fly Treatment Today
If you’re noticing flies gathering in your loft, don’t wait until the problem worsens. Contact Malvern Pest Control today for a professional inspection and treatment. Call us directly, or use our online booking form to arrange a fast, local service.