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The Tachinidae are a large and variable family of true fly within the insect order Fly, with more than 8,200 known species and many more to be discovered. Over 1,300 species have been described in North America alone. Insects in this family commonly are called tachinid flies or simply tachinids. As far as is known, they all are protelean parasitoids, or occasionally parasites, of , usually other insects. The family is known from many habitats in all Zoogeography and is especially diverse in South America.
The valid full name (with author) of this taxon is therefore Tachinidae Robineau-Desvoidy, 1830.
There may be confusion between this family name and its homonym used by Fleming in 1921 to describe a family of Coleoptera. The latter usage was invalidated by the ICZN in 1993 (Opinion 1743), which corrected the spelling of Tachinidae Fleming, 1821 (Insecta, Coleoptera) to Tachinusidae to avoid homonymy with Tachinidae Robineau-Desvoidy, 1830 (Insecta, Diptera).
() of most members of this family are (developing inside a living host, ultimately killing it). In contrast, a few are parasitism (not generally killing the host). Tachinid larvae feed on the host tissues, either after having been injected into the host by the parent, or penetrating the host from outside. Various species have different modes of oviposition and of host invasion. Typically, tachinid larvae are (internal parasites) of of butterflies and moths, or the eruciform larvae of Sawfly. For example, they have been found to lay eggs in Eldana larva, a species of moth common in sub-Saharan Africa, as well as the more northerly Arctic woolly bear moth. However, some species attack adult and some attack beetle larvae. Others attack various types of , and others attack ; a few even attack . Also parasitised are bees, wasps and sawflies.
Many other species inject eggs into the host's body, using the extensible, penetrating part of their ovipositor, sometimes called the oviscapt, which roughly translates to "egg digger". Species in the genera Ocyptera, Alophora, and Compsilura are examples.
In many species only one egg is laid on or in any individual host, and accordingly such an egg tends to be large, as is typical for eggs laid in small numbers. They are large enough to be clearly visible if stuck onto the outside of the host, and they generally are so firmly stuck that eggs cannot be removed from the skin of the host without killing them. Furthermore, scientists have observed in studies with the host cabbage looper that being glued to the host insect helps maggots burrow into the larva, where they remain until fully developed.
Yet another strategy of oviposition among some Tachinidae is to lay large numbers of small, darkly coloured eggs on the food plants of the host species. Sturmia, Zenillia, and Gonia are such genera.
Many tachinids are important natural enemies of major insect pests, and some species actually are used in biological pest control; for example, some species of tachinid flies have been introduced into North America from their native lands as to suppress populations of alien pests. entomology.Wisconsin.edu. Compsilura concinnata, Parasitoid of Gypsy Moth Conversely, certain tachinid flies that prey on useful insects are themselves considered as pests; they can present troublesome problems in the sericulture industry by attacking silkworm larvae. One particularly notorious silkworm pest is the Uzi fly ( Exorista bombycis).
Another reproductive strategy is to leave the eggs in the host's environment; for example, the female might lay on leaves, where the host is likely to ingest them. Some tachinids that are parasitoids of stem-boring caterpillars deposit eggs outside the host's burrow, letting the first instar larvae do the work of finding the host for themselves. In other species, the maggots use an ambush technique, waiting for the host to pass and then attacking it and burrowing into its body.
Adult tachinids are not parasitic, but either do not feed at all or visit flowers, decaying matter, or similar sources of energy to sustain themselves until they have concluded their procreative activities. Their non-parasitic behaviour after eclosion from the pupa is what justifies the application of the term "protelean".
Adult flies feed on and nectar from and . As many species typically feed on pollen, they can be important of some plants, especially at higher elevations in mountains where bees are relatively few.
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 on the immature stage.
target="_blank" rel="nofollow"> Stireman, J. TACHINIDAE: Evolution, Behavior, and Ecology
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