The family Tachinidae is one of the most important families of flies. Well over 1500 species are known for our continent and more than 5000 species have been named for the entire world. Their chief value to man lies in their parasitic habits. Many of the species are highly destructive to injurious insects, especially the caterpillars of the Lepidoptera. Their usual procedure is to search out a prospective host and attach one or more eggs to the surface, often in some place which the victim cannot reach with its jaws. The maggot upon hatching immediately enters its host and lives in the open blood sinuses where the nutriment is rich but no vital parts of the host are injured. The maggots may leave their host when they have completed their growth and pupate in the ground or other protected place, but in the case of many species remain within the host to pupate and later emerge as an adult. The host caterpillar frequently pupates before the maggot has completed its growth. That makes but little difference to the tachinid larva which then feeds upon the contents of the pupa and in turn pupates within it. Presently, then, instead of a moth or butterfly emerging from the pupal case one or more tachinid flies appear.
Proceedings of the Iowa Academy of Science
©1949 Iowa Academy of Science, Inc.
Jaques, H. E.
"A report on the Iowa Species of Tachinidae (Diptera) in the Iowa Insect Survey Collection,"
Proceedings of the Iowa Academy of Science, 56(1), 363-365.
Available at: https://scholarworks.uni.edu/pias/vol56/iss1/50