Tachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. There are over 1300 species in North America. Insects in this family are commonly called tachina flies or simply tachinids. As far as is known, they all are Protelean parasitoids, or occasionally parasites, of Arthropoda.
The family is cosmopolitan. Species occur in many habitats in many regions, including Neotropical, Nearctic, Afrotropical, Palaearctic, Oriental, Australasian and Oceanic.