These insects are born out of earthworms if you can believe that and like to overwinter in protected areas.
Flies in attic winter.
Flies that gather in roofs around windows and on walls inside in the autumn and winter are called cluster flies also known as attic flies.
Most commonly they move from the ground to your attic for the winter when it gets cold.
Attic flies which are also known as cluster flies are insects that often migrate into homes in the fall where they hibernate for the cooler fall and winter months.
Attic flies common this winter by donald lewis department of entomology the large black pesky flies that show up in bed rooms and on window sills from late fall through early spring have been very abundant this year possibly because of the wetter than normal weather we had last summer.
By instinct they seek shelter away from the elements such as in the fall when it gets cold.
Flies are an expected nuisance in the spring and summer but some homeowners will find themselves in the midst of an infestation in cold winter months.
Entry entering living spaces by way of electrical outlets or baseboards the pests take shelter in attics and walls to hibernate awaiting the arrival of warmer spring weather.
One of the best tips for getting rid of attic flies is to keep them from entering the house in the first place as trying to eliminate them after they are in hibernation can be difficult.
These eggs hatch throughout the winter and the little flies have nowhere to go but the home.
Cluster flies prefer warm areas so homeowners often find them flying around houses on sunny days in the winter and late fall months.