When louse flies breed, the larvae develop inside the mother, before being deposited to pupate.
Louse flies are mostly found on birds, and sucks blood through a short proboscis. However, the flies are also found in nests where you can also find the overwintering pupae, while the birds have migrated south during the winter. From the nests, the lice flies can sometimes stray into homes. This probably only happens if the birds, for some reason, leave the nest during the breeding season, or if the bird do not return to a nest in which louse flies are overwintering. Louse fly innovations happen in the months from April to August, mostly in June. Furthermore, you can get in contact with louse flies, if you are handling a dead bird. Louse flies rarely bite humans, but their flat body and crab-like walk make them appear rather eerie. They cannot live or multiply in human homes.