Cluster fly adults emerge from the ground in late summer/early autumn. … It is because of this that they are sometimes known as ‘attic flies’. A large number of flies flying around the property, or dead flies on window sills, will be a good indication that a swarm has taken up residence in your property.

Why am I finding dead flies in the house?

Active and dead flies found in your house is most likely from dead animals in your walls. Mice and rodents can easily get into the walls of your home and die and the flies feed off of them.

How do I get rid of dead flies?

Use a vacuum or broom to remove the dead insects. Be sure to remove the dead insects before treating with a residual insecticide spray and dust. Space and contact sprays will only kill the flies that are exposed at the time of the application.