How do I get rid of Cluster Flies?

Adult male cluster fly

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About Cluster Flies

Similar in size to the house fly, the cluster fly (attic fly) is common throughout the UK. Whilst they do not represent a health problem as such, they become a nuisance when searching for ideal hibernation locations, usually in late summer/early autumn.

Large numbers of adult cluster flies can enter houses and buildings, seeking warmth and shelter in unoccupied and inaccessible areas such as wall cavities and roof spaces.

Electric Cluster Fly Killers

If an electrical supply is available, installation of a high capacity electric grid fly killer (zapper) like the Insect-a-clear T160 will be an effective solution. Flies are attracted to the ultraviolet light in the device and then either captured on a board coated in glue or 'zapped' when flying into an electrified grid.

Where the location is not easily or regularly accessed, it may be safer to install a glue board fly killer as there can be a small potential fire risk from arcing where electric grid units become full of fly bodies.

The Fusion range of fly killers from Insect-a-clear make a good choice for cluster flies owing to their use of double-sided glue boards for maximum capacity.

Alternatively, if you would prefer to use an electric grid fly killer, then consider using an extra deep cluster fly collection tray to give the machine a greater capacity for storage of the resulting fly bodies.

Fly Sticks/Papers

Where there is no existing electrical supply, then a fly stick or sticky fly papers can still offer a very effective solution for cluster flies.


Aerosol fly sprays can be used effectively on small groups of cluster flies but where the numbers are very large, an insecticide ‘fogger’ like the Lodi Insecto Pro Formula Insect Fogger offers a highly effect solution.

Activated and left to work for a number of hours, these devices fill the whole area with an insecticide fog which kills all cluster flies exposed to it. Once it is safe to enter the area again, the fly bodies can then be vacuumed up and disposed of. It is very important to follow the instructions on insecticide products carefully.

How can I prevent Cluster Flies returning?

Control of cluster flies is most effectively achieved by providing a physical barrier to entry. Where possible, you should block any openings that could give flies access to your property. Look for missing or damaged roof tiles, bricks or mortar and any gaps around windows and doors.

Where an opening is required, for example air bricks, Mouse Mesh offers a solution, allowing the free flow of air but acting as an effective barrier to insects and rodents.

Take a look at our range of Cluster Fly machines and accessories.

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