Tachinidae
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{{Taxobox | color = pink | name = Tachinidae | image = Tachinidae_Gymnocheta.jpg | image_width = 250px | image_caption = Gymnocheta sp. | regnum = Animalia | phylum = Arthropoda | classis = Insecta | subclassis = Pterygota | infraclassis = Neoptera | superordo = Endopterygota | ordo = Diptera | infraordo = Muscomorpha | subordo = Brachycera | superfamilia = Oestroidea | sectio = Calyptratae | family = Tachinidae | subdivision_ranks = Subfamilies | subdivision =
}}
Tachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and probably many more to be discovered. There are over 1300 species in North America
Insects in this family are commonly called Tachinid flies.
They occur in almost all habitats all over the world. There are Neotropical species, Nearctic, Afrotropical, Paleoarctic, Oriental, Australasian and Oceanic species.
A typical characteristic of this family is the fact that larvae are endoparasites (internal parasites) of caterpillars of butterflies and moths, adult and larval beetles, sawfly larvae, various types of true bugs and grasshoppers, rarely in centipedes, with usually only one grub. Only a few species are host species-specific. As such, many are important natural enemies of major pests. Some species are being used in biological pest control. Many important pests are suppressed by tachinids. Many species of tachinid flies have been introduced into North America from their native lands as biocontrols to suppress populations of alien pests. Image:Eriothrix rufomaculata.jpg
Tachinid flies are however regarded as pests by silkworm rearers. One particularly noted species is the Uzi fly (Exorista bombycis).
The female may lay her white oval eggs on the skin of the host insect, or insert the egg into the host's body, or leave them in the host's environment, as for example on leaves, where the host will ingest them. The larvae feed on the host tissues, causing death.
Tachinid flies are extremely varied in appearance. Adult flies may be brilliantly colored and then resemble blow-flies (family Calliphoridae), or rather drab, and then resemble house flies.But tachinid flies are more bristly and more robust. They have three-segmented antennae, a prominent postscutellum bulging beneath the scutellum (a segment of the pronotum), bare (sometimes plumose) arista. The thoracic squamae (small scales above the halteres) are usually very large. Their fourth long vein bends away sharply.
Adult flies feed on flowers and nectar from aphids and scaless As they typically feed on pollen, they can be important pollinators of some plants.
The taxonomy of this family presents many difficulties. It is largely based on morphological characters of the adult flies, but also on reproductive habits and the immature stage.