The main periods of activity are in the autumn when the flies are coming in, and again in the spring when they come out of hibernation. They can be a nuisance during the winter months when the heating within houses and buildings wakes them up prematurely and they enter the living space through loft hatches and light fittings. They can also be found within the space between windows and window frames.
It is recommended to treat these insects after the first frosts of winter by which time the majority of these flies will be in residence.
Treatments are relatively simple and effective for these seasonal flies.