Cluster flies don’t bite and they’re not out to sting you, but when they settle in lofts and roof spaces the numbers can be ridiculous. In Glasgow, East Kilbride and across Lanarkshire we often hear the same story: bright day, sunny window, and suddenly there’s a wee heap of flies on the sill or a low drone coming from the attic. That’s when our cluster fly pest control work begins.
What Are Cluster Flies?
They’re not your usual house fly (Musca domestica) and they’re not the small, zippy lesser house fly (Fannia canicularis) either. Cluster flies are slower, a bit lazier in flight, and they like company. Unlike fruit flies that turn up around bins or fermenting fruit, their life cycle starts in soil and the larvae develop inside earthworms — which is why they appear from nowhere and don’t care about your kitchen scraps.
They’re dark flies with a dusting of gold/silver hairs and a habit of ducking indoors to hibernate in autumn — exactly what we see locally. They’re not a major food-contamination risk like drain flies can be, but in big numbers they’re a pain to live with and a classic cluster fly infestation to sort.
Why Do They Pile Into Roof Spaces in Autumn?
As temperatures dip, cluster flies look for sheltered spots. Loft voids and roof spaces fit the bill. One fly finds a decent nook, leaves a chemical “come this way” signal, and the rest follow. The Bat Conservation Trust explains that they gather on outside walls in late autumn, then move into cooler loft areas for winter — and the same buildings tend to get them back every year. If soffits, vents and gaps around the roofline aren’t sealed, they’ll keep returning.
Signs of a Cluster Fly Infestation
Not sure if it’s cluster flies or just the odd housefly? Some signs to watch out for include:
- Piles of dead flies on sunny window sills
- Large numbers buzzing in lofts or roof spaces
- A faint, musty smell in heavy infestations
- Flies reappearing in the same spots every autumn
If you’re still not certain, we can carry out an inspection and confirm the insect identification for you.
Managing Cluster Flies Through the Season
People often grab the hoover or a can of fly spray to deal with the problem, the British Pest Control Association (BPCA) advises just this it says: “Cluster flies can often most easily be removed with a vacuum cleaner. Aerosol fly killers deal with smaller numbers.” and while that tidies things up for a bit, it rarely solves it long-term. Cluster flies have a habit of returning to the same property year after year.
To really get on top of them, targeted pest control treatments may be needed. In some homes, fly screens or electronic fly killers make a difference too. At Strathclyde Pest Control, we tailor our fly control services to each property — whether it’s a single loft space or a larger site with waste management areas and bright light sources that attract flies.
Our Approach at Strathclyde Pest Control
Here’s how we handle cluster fly pest control in Glasgow and Lanarkshire:
- Inspection – we look for entry points around vents, soffits, and roof gaps.
- Treatment – depending on the severity, we use residual insecticides, aerosol fumigation devices, or knockdown spray treatments.
- Proofing – we advise on sealing entry points and may suggest extras treatments if needed.
- Follow-up – if flies reappear later in the season, we can revisit to keep things under control.
As a local pest control company, we also deal with a range of other problems — from bed bugs and fleas to rodent control and bird control. Feel free to contact us about any of these issues.
Final Word
Cluster flies may not sting like wasps or chew wires like grey squirrels, but the nuisance is just as real. If you’re finding buzzing flies in your loft every year, chances are they’ve made your property a regular stop-over.
Strathclyde Pest Control provides fast, discreet, and effective cluster fly pest control services across Glasgow, East Kilbride, and Lanarkshire. Whether it’s a one-off problem or part of wider insect control, our pest control specialists are ready to help.
Call 07825 557794 today or contact us online to book your inspection.
Cluster Flies FAQs
Q: What makes cluster flies different from houseflies?
Cluster flies are chunkier and slower than the buzzing houseflies you’ll find around bins. They tend to group together in roof spaces or by windows. Unlike blowflies (Calliphora vicina, Calliphora vomitoria) or the common housefly, they don’t breed in food waste – their young actually develop in earthworms outdoors.
Q: Why do they keep appearing every autumn?
It’s down to their behaviour. As soon as the weather cools, cluster flies look for warm buildings to hide out in. One fly gets in, releases a scent, and suddenly you’ve got a cluster fly infestation.
Q: Do they bite or carry disease?
No – cluster flies don’t bite people and aren’t linked to food contamination. The main issue is the nuisance: piles of flies, buzzing, and in heavy infestations, a stale smell.
Q: What’s the best way to get rid of cluster flies in your Glasgow home?
Residual sprays, insecticidal fogging, and fly control services carried out by a professional pest control service give the best long-term results. DIY swatting or fly sprays usually only give short relief.
