Cluster Flies Autumn
Autumn is the time when PEST UK start receiving enquiries about Cluster Fly Removal.
Cluster Flies are amazing creatures because of the genetic memory they are meant to possess – this also makes them difficult to eradicate.
Cluster Flies pick a hibernation site. The exact criteria for this choice is unknown but it is usually on one side of a building, often on the south side. Once the site has been selected the site will always be used. Cluster Fly insecticide treatments will relieve the problem but rarely eradicate it.
The reason that complete extermination is difficult is that, assuming there is an infestation in the loft which is treated with 100% success, the flies will also be using the wall cavities and soffits and also areas between the felt and the tiles. When spring arrives Cluster Flies will start to leave – this is a gradual process and may take several weeks. Flies will come out of the site during the warmer part of the day and then go back in at night. This process will be repeated until they don’t go back in at all.
The most common f Cluster Fly has the following life cycle:
- Once they leave properly they mate and the females lay eggs in the soil.
- These eggs hatch into grubs which bore into the soil in search of an earthworm.
- Once found the grub is parasitic on the earthworm.
There are other species of Cluster Fly, the next most common one breeds in dung heaps so areas near farms are susceptible to Cluster Fly infestations.
What is remarkable is that the descendants go back to the hibernation sites that their great grandparents came from. The Cluster Flies that emerge from hibernation will die shortly after mating and laying eggs and there may be several generations in the Spring, Summer and Autumn before the Cluster Flies hibernate.