Cluster Flies

What do Cluster Flies look like?

The common cluster fly is very similar in appearance to house flies however they have yellowish golden hairs on the thorax and a pattern on their abdomen, they also tend to be sluggish movers.

Do Cluster Flies carry germs or diseases?

The grass flies or cluster flies are not considered to be a threat to human health.

Do Cluster Flies bite or sting?

No Cluster flies are more or less harmless apart from the fact that they crawl everywhere which can help to spread bacteria to different surfaces.

What damage do cluster flies do?

Cluster flies leave tiny dark-coloured spots of excrement on walls or windows which can be difficult to clean. Cluster flies that die in areas such as wall voids or false ceilings, may attract other scavenging pests such as larder beetles.

A few more facts about Cluster Flies

  1. Cluster Flies lay eggs in the soil in gardens fields often near to earthworm runs.
  2. The hatched larvae then attach themselves to earth worms and feed on them.
  3. Flies don’t really go back to their previous years winter harbourage, most will have died off, it is their offspring that go back to where the same places this is thought to be down to pheromone attraction.
  4. The larvae of Cluster Flies are actually a parasitic, attaching themselves to and living on earth worms prior to becoming flies.
  5. The name Cluster Flies is due to the way in which they cluster together as the temperatures drop and go into a state of hibernation.

As autumn arrives cluster flies gather in large numbers on sun-warmed, south-east facing walls during the day. They crawl into crevices or under eaves, tiles, window frames etc and make their way into the roof space of houses. As the temperatures drop they group together often appearing to have gone, however they will be ‘clustered’ together under roof linings and any other cracks and crevices in the roof, windows or walls. Once the weather warms in the spring, cluster flies become active again, leaving their winter harbourages, in the summer they lay their eggs in the soil eventually pupating and attaching themselves to earthworms for food, emerging as adult flies to look for their winter harbourages.

How to get rid of cluster flies

Cluster flies can enter your home through the smallest of cracks around door and window frames or through other tiny openings. You can limit access to the building by filling cracks and crevices in walls, window or door frames with caulking. However, you’re highly unlikely to stop all of them getting in, other than insecticidal treatment there are few ways to control their numbers. Aerosol insecticides will kill all flies that it hits however due to the nature of Cluster Flies they are often hidden away in their hundreds or even thousands where an aerosol will not get to them, this where a professional pest controller is needed, having the appropriate equipment and an understanding of the requirements for a successful treatment.

Get in touch with Lincspest today for prevention and removal of cluster flies. We offer pest control services in Lincolnshire and surrounding areas.

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