Professional Cluster Fly Treatments
- NPTA Approved Business
- Qualified Pest Technician
- Trusted Local Business
- Discreet Service Provided
- Latest Industry Methods
Important Notice on Cluster Flies and Seasonal Pest Treatments
Due to the increasingly warmer weather in the UK, managing cluster flies and other seasonal flying insects has become more challenging than ever. As these pests adapt to changing conditions, our treatment options are somewhat limited, and each situation requires a unique approach. We understand that dealing with these pests can be frustrating, and we're here to help. If you are experiencing issues with cluster flies or other seasonal insects, please don't hesitate to reach out to us. Our team is committed to discussing your specific needs and providing the most effective solutions available.
Common Signs Of A Cluster Fly Infestation
- Large numbers of flies are building up around southern facing windows, or the sunniest side of the property.
- Flies are building up in loft areas or you notice lots of dead flies on the boarding or insulation in roof voids.
- Flies appear out of framework when you open windows, you may also spot small brown spots around the window casings/frames.
- A strong sickly sweet aroma can be smelt in upper floors or when entering a roof space, this is the cluster fly pheromone.
Cluster Fly Control FAQ's
Most frequent questions and answers
Call a professional pest control company, like ourselves, who has access to professional use only insecticides and the experience and knowledge of how and when to use those products. In the long run this will save you time, money and get the issue under control much quicker.
Yes. When being used by a trained professional. We only use the necessary product amounts that are required for each treatment we carry out.
The best time is when the weather has cooled down in the Autumn months. Temperatures below 10°c will help as the flies will tend to remain within the property.
However the effects of temperatures rising globally has caused issues over the last few years with timings of treatments.
Cluster flies require somewhere warm and dry to hibernate over the winter months. When they find a suitable location (your property) they will find ways in through gaps, cracks, holes or under roof tiles to gain entry. When they enter and exit the property they leave a pheromone to mark the property. This helps them locate their safe space upon their return. This also tells other flies and insects where a good spot to hibernate is! The more flies, the more pheromone which means more flies/insects numbers build.
Unfortunately it is very rare that one treatment will put an end to cluster fly activity at a property. Multiple treatments are usually required to tackle this persistent pest species.
The more treatments you have, gradually the fewer flies you should get each year.
If you have bats roosting in your loft, we can’t treat this area. In Britain all bat species and their roosts are legally protected, by both domestic and international legislation. More information is available by clicking here.
Where Do We Offer Cluster Fly Control Services
We proudly offer our services across a substantial portion of Hampshire. While our primary focus is within this region, we are flexible and open to traveling for work when necessary. Our main areas of operation include Andover, Winchester, and Alresford. Additionally, we extend our services to the surrounding areas, ensuring comprehensive coverage for your convenience.
Surrounding Areas
Andover:
Charlton, Enham Alamein, Thruxton, Hurstbourne Tarrant, Abbotts Ann, Weyhill, WhitchurchWinchester:
Shawford, Twyford, Kings Worthy, Littleton, South Wonston, Sparsholt, Hursley, Micheldever, Sutton ScotneyAlresford:
Ropley, Bramdean, Bighton, Cheriton, Tichborne, Old Alresford, Bishop’s Sutton, Itchen StokeStockbridge:
Chilbolton, Kings Somborne, Broughton, Longstock, Middle Wallop
We are committed to delivering exceptional service to these communities and beyond. If you reside outside these areas, please feel free to reach out, as we are more than willing to accommodate your needs.
What our customers say about our pest services
EXCELLENT Based on 31 reviews Posted on Alix Baker23 September 2025Trustindex verifies that the original source of the review is Google. George came within an hour of me calling him and promptly found and dealt with the problem. Excellent service.Posted on Chris Taylor20 September 2025Trustindex verifies that the original source of the review is Google. Really fantastic service. George was able to quickly and efficiently help us after we discovered a wasp nest under our roof tiles. One visit was all that was needed, he talked us through the whole process and kindly provided helpful advice for how we can avoid similar issues in the future. Will definitely use again if we have any other pests in the future.Posted on Robin Ashfield23 August 2024Trustindex verifies that the original source of the review is Google. Fantastic response time and thoroughly professional job of extracting wasps nest that had damaged electrics. George's attitude was exceptional, "I'm not leaving until this is fixed" gets him a YES from me.Posted on Charlotte Jobson15 December 2023Trustindex verifies that the original source of the review is Google. I recently had the misfortune of discovering loud noises in the loft, and needless to say, panic set in. After a quick search for reliable pest control services, I stumbled upon Bentley Environmental Pest Services, and I can confidently say that their service was nothing short of outstanding. From the moment I called George he was top-notch and was very prompt in taking action. After strategically placing cameras, George efficiently installed the right traps. It was a comprehensive solution that showcased his dedication to resolving the issue effectively. His daily communication was a game-changer. Updates on the surveillance results and progress kept me informed at every step. George exceeded my expectations with his tech-savvy approach, personalised service and unwavering commitment to communication. I highly recommend his outstanding pest control services for anyone dealing with a similar situation and I will be engaging on a maintenance plan going forward.Posted on Dani Burnett7 September 2023Trustindex verifies that the original source of the review is Google. Would highly recommend Bentley environmental who came out today to treat a wasps nest in my porch! I'm all about customer service and I couldn't fault him! He was friendly, chatty and just a smashing guy! Professional and got the job done quickly!Posted on Peter Whyte18 July 2023Trustindex verifies that the original source of the review is Google. Excellent prompt service - wasps nest dealt with efficiently and safely. A very professional service. Many thanks George.Posted on Andrew Coombes2 July 2023Trustindex verifies that the original source of the review is Google. Came quickly, very knowledgeable about the subject, cured the problem. Would definitely recommend.Posted on mrlb medicalservices1 June 2023Trustindex verifies that the original source of the review is Google. We cannot recommend George highly enough. He was extremely professional, easy to reach and made us feel very comfortable and confident in his ability. George kept us up to date regularly and talked through all options frequently. George went above and beyond and talked us through everything he was doing. He was very fair with his costs and didn’t do anything without the okay first. We can absolutely recommend George for any pest problems. If ever we have a problems in the future. He will be our first call. Thank you George for your help and professionalism.Posted on Elizabeth17 January 2023Trustindex verifies that the original source of the review is Google. George is extremely knowledgeable with rodent control, I would recommend him to my friends and family. Thank you for your professional service. Elizabeth, SwanmorePosted on Chris Peters19 October 2022Trustindex verifies that the original source of the review is Google. Wasps nest treated quickly and informed of the process step by step. Very happy with the service and friendly approach. Would highly recommend!
We appreciate everyone can get a little busy.
So fill in our form below and we'll get back to you whenever suits you best.
So fill in our form below and we'll get back to you whenever suits you best.
Further Information On Cluster Flies
Cluster Flies: Understanding and Managing Infestations
Cluster flies, often found throughout Europe and the UK, are a common concern for homeowners. While these flies are harmless and do not carry diseases that affect humans, they can become a nuisance when they gather in large numbers. Here, we explore cluster fly behavior and effective methods for managing infestations.
What Are Cluster Flies?
Cluster flies derive their name from their habit of clustering together in large numbers to overwinter. Several species exist in the UK, often found in mixed swarms. These flies vary in size, ranging from 3 to 8mm in length. Only adult flies overwinter, beginning their clustering behavior around September.
Once cluster flies locate a suitable site to hibernate, they release a pheromone that attracts other flies. This pheromone can sometimes be detected by a sickly sweet smell when large numbers are present. Remarkably, cluster flies often return to the same site year after year, increasing the importance of effective treatment.
Lifecycle of Cluster Flies
Cluster flies emerge in early spring, congregating on walls, roofs, fences, and trees to soak up the sun’s warmth. Following this, they fly off to lay their eggs, typically in turf, leaf litter, compost heaps, or muck heaps. Once hatched, the larvae, which are parasitic, seek out earthworms, boring through their skin to consume them alive. After the worm’s demise, the larvae pupate in the surrounding soil, and adult flies feed on nectar from garden and wildflowers.
Seasonal Behavior
During the summer months, cluster flies are generally not a nuisance. However, as autumn approaches, they become more problematic as they invade homes and offices, particularly in rural areas. They typically cluster in roof spaces, window frames, or other suitable locations to hibernate through the winter.
Treatment Options
To manage a cluster fly infestation, we offer comprehensive treatments:
Loft/Roof Space Treatment: We use insecticidal aerosol total release sprays or cold fogging/ULV (Ultra Low Volume) equipment. These methods effectively kill flies within lofts, reducing their numbers in and around the property.
Internal Window Framework Treatment: After cleaning the frames to remove any pheromone, we apply a residual insecticide. Flies absorb this insecticide through their bodies upon contact, helping to control their population.
The number of treatments required can vary. While minor infestations may only need a single treatment, heavier infestations often require several treatments over a few years to reduce the cluster fly population to satisfactory levels.
Challenges and Considerations
With global temperatures rising, pest controllers face new challenges as flies come and go more frequently due to fluctuating autumn temperatures. Therefore, treatments for cluster flies in the UK are most effective after the first frosts of the season.
Completely sealing a building to prevent fly entry is rarely possible. However, sealing gaps around window frames, skylights, and other potential entry points can significantly reduce the likelihood of an infestation.
By understanding cluster fly behavior and implementing effective treatment strategies, homeowners can manage these pests and minimize their impact on living spaces.

Electronic Fly Killer Units
We also supply and install Electronic Fly Killer Units (EFK's)
Ideal Installation Locations
For commercial settings, our units are most commonly installed in kitchens and dry goods storage areas, ensuring effective pest control in these critical spaces. In domestic environments, loft areas are the preferred installation sites, providing effective coverage and pest management.
Comprehensive Pest Control
Our solutions are not limited to controlling cluster flies during their active season; they are also effective against a variety of other flying insects, including moths and wasps that may enter through open doors and windows. This provides you with the peace of mind of year-round fly control.
Product Options
We offer a range of Electric Fly Killers (EFKs) to suit different needs. Choose from our commercial-style units or opt for our discreet domestic units designed to seamlessly blend into home environments.
Installation Requirements
Electrical Access: Our EFKs require installation near a plug socket within 3 meters. Should additional electrical points be necessary, customers will need to arrange for an electrician.
Insurance Considerations: Before installation, please verify with your home insurer that your existing policies remain unaffected, particularly for installations in loft areas.
Bat Activity: We can only proceed with installations in lofts if there is no bat activity present. Please ensure this condition is met.
Our team is dedicated to providing effective and safe pest control solutions tailored to your needs. Contact us for more information or to schedule an installation.

We can only install these units within loft areas if no bat activity is present.
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