The friendly fly or large flesh fly,
''Sarcophaga aldrichi'', is a fly that is a
parasitoid of the
forest tent caterpillar
The forest tent caterpillar moth (''Malacosoma disstria'') is a moth found throughout North America, especially in the eastern regions. Unlike related tent caterpillar species, the larvae of forest tent caterpillars do not make tents, but rathe ...
. It strongly resembles the
house fly but is in a different family, the Sarcophagidae, or
flesh-flies. It is a little larger than the house fly, and has the same three black stripes on its
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
. It has red eyes, a grayish body, and a checkered abdomen.
In early summer it emerges from
pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...
e in the ground and seeks out forest tent caterpillar cocoons, where it deposits live larvae which bore into the cocoons and feed on the pupating insects, killing them. Eventually the fly
maggot
A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and crane flies.
...
s drop to the ground and pupate and go dormant over the winter.
Population explosions of this species usually occur during the summer following the one when the caterpillars are plentiful. The friendly fly can be a nuisance, but they don't bite, nor do they spread disease. This species is sometimes referred to as the "government fly", because when the population explosions do occur, sometimes a rumor goes around that the flies were deliberately released by a government agency, in a misguided environmental program.
References
External links
Government warning concerning the Government Fly
Sarcophagidae
Diptera of North America
Parasitic flies
Insects described in 1916
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