Seeing an infestation in your loft can be quite daunting, especially when you learn that the problem is a case of management rather than elimination. However these flies are really easy to kill and there are long term insecticides which really help manage the issue. It is also worth mentioning that you won’t ever have to deal with the other stages of the life cycle of a cluster fly as they only enter a property in the search for somewhere to hibernate.
Dealing with the issue short term and eradicating hundreds or thousands at once:
The fastest way to knock down the fly population in one area is by fumigating. You can do this using either a Formula P Power Fogger or a Formula P Smoke Bomb. These fumigation devices will kill all flies in the airspace and any that enter whilst the chemical is still present and makes the treatment process much easier when access to the area is tricky.
Long term protection against cluster flies:
The most effective treatment long term would be following the fumigation process with either the Formula P Powder or the Formula C Spray. Both of these insecticides will remain effective for up to 12 weeks and so when applied to various surfaces, continuously kill the cluster flies during this time. As the cluster flies enter when it starts to get cold in late September/October, applying the spray once can often see the treatment right through to the end of the season.