Overview
A large, cosmopolitan family, popularly known as 'blowflies' - derived from 'blue' fly, referring to species of the Northern Hemisphere. Here it is largely a misnomer. They include some serious economic pests of livestock. Eggs are laid on the animal's body where the larvae attack weakened or broken tissue. The resulting, extensive lesions, especially if extended by 'secondary' species, may lead to death of the host. In Australia the chief offender is the green sheep blowfly,
Lucilia cuprina
(Wied.), but we also live under the threat of receiving the Oriental screw-worm fly (
Chrysomya bezziana
Villeneuve), which is already present in New Guinea.
Four subfamilies are present in Australia. The recently erected Aphyssurinae includes only the genus
Aphyssura
, with 27 species. The Calliphorinae are well represented, with 54 described species (and an unknown number yet to describe); 41 are endemic. The principal genera are
Calliphora
and
Onesia
. The Chrysomyinae include only the genus
Chrysomya
, with eight species, only one endemic, while the Rhiniinae have 15 species in four genera. The Ameniinae are well represented by 22 species, all endemic, principally in genus
Amenia
.
Adults are strongly attracted to moisture, feeding on sweet liquids such as nectar or the exudates of decomposing carrion. Some species of
Calliphora
thus play a role in the pollination of eucalypts. Many deposit larvae rather than eggs, and
Calliphora ochracea
is well known for leaving its maggots on the blankets of campers. Larvae live in any form of decomposing organic matter. Apart from those causing myiasis (mentioned above), many are notable breeders in carrion, some as predators on other larvae. However, some species of
Calliphora
parasitise earthworms, as do species of
Onesia
and
Pollenia
. Larvae of at least some Rhiniinae live in nests of ants or termites and the Ameniinae are notable in that, as far as known, all are parasites of snails.
Description
Most adults are fairly stout flies, metallic blue or green in several species, but mostly drab. Vein M is curved or angled forward towards R4+5, the anepimeron and meron are bristled, and the arista is usually plumose (except in
Aphyssura
and Rhiniinae). There is no subscutellum, except for a weak one in Ameniinae; but those are distinguished by the posterior spiracle, which almost always has a tuft of long setae on the anterior lappet, and the face with a strong keel-like carina (except in
Paramenia
).
Distribution
Apart from well known cosmopolitan immigrants, we share relatively few species with neighbouring countries. For instance, we have seven described species of
Pollenia
, all endemic, whereas New Zealand has some 35. Our endemic Ameniinae, Chrysomyinae and Rhiniinae tend to be distributed mainly in the north, presumably due to relatively recent entry from that direction. By contrast,
Calliphora
and
Pollenia
seem to have radiated in the moister, cooler regions. It is noticeable, too, that the parasitic Ameniinae and Rhiniinae have the widest distributions in Australia.