The name Cluster Fly refers to their habit of clustering together in large numbers to over winter. There are several species found in the UK, and they can be found in mixed swarms. These sizes vary between species to species ranging from 3 to 8mm in length Only adult flies over winter these start to cluster from early September onwards.
Once they have found a suitable site to hibernate they emit a pheromone which attracts others, its quite possible if the numbers clustering are larger enough too smell there pheromone, this is a sickly sweet smell.
They will return year after year to the same site in ever increasing numbers.
They emerge in early spring congregating on a sunny walls, roofs and fences etc to warm up in the sunshine. They then fly off to lay there eggs, these are laid in leaf litter, compost heaps, or muck heaps. Once hatched the larva which are parasitic seek out earthworms, they then bore through the worms skin and proceed to eat it alive. When the worm dies the larvae emerge and pupate in the surrounding soil, the adult flies feed on the nectar of garden and wild flowers.
During the summer, cluster flies are not a nuisance, only as the autumn approaches do they become a pest as they start to invade peoples house’s and offices.
Please call us to treat your cluster fly problem.