Photo by Drees. Photo by Jackman. Adult tachinid flies can superficially resemble houseflies, but vary by species in size, coloration and shape. Many are gray or black or have bodies marked with stripes. Many have distinct long bristles on the ends of their abdomens.
Life cycles vary by species.
Eggs are sometimes laid on leaves and ingested by a host caterpillar during feeding. Female flies of other species may glue their eggs to the hosts body after which the hatching larva tunnels inside. In other species, eggs are inserted directly into the hosts body by the female. Adults emerge 1 to 2 weeks later. Depending on species one or more generations occur per year.