Blowflies belong to the Calliphoridae family and have to rank amongst the least loved of all our insects.
Calliphoridae adults are commonly shiny with metallic colouring, often with blue, green, or black thoraxes and abdomen. Antennae are 3-segmented, aristate. The arista are plumose the entire length, and the second antennal segment is distinctly grooved. The characteristics and arrangement of hairs are used to tell the difference between members of this family.
The current theory is that females visit carrion both for protein and egg laying, but this remains to be proven. Blow-fly eggs, usually yellowish or white in color, are approximately 1.5 mm x 0.4 mm, and, when laid, look like rice balls. While the female blow-fly typically lays 150-200 eggs per batch, she is usually iteroparous, laying around 2,000 eggs during the course of her life. The sex ratio of blowfly eggs is usually 50:50, but one interesting exception is currently documented in the literature. Females from two species of the genus Chrysomya (C. rufifacies and C. albiceps) are either arrhenogenic (laying only male offspring) or thelygenic (laying only female offspring).
Hatching from an egg to the first larval stage takes about 8 hours to one day. Larvae have three stages of development (called instars); each stage is separated by a molting event.The instars are separable by examining the posterior spiracles, or openings to the breathing system. The larvae use proteolytic enzymes in their excreta (as well as mechanical grinding by mouth hooks) to break down proteins on the livestock or corpse they are feeding on. Blowflies are poikilothermin, which is to say that the rate at which they grow and develop is highly dependent on temperature and species. Under room temperature (about 20 degrees Celsius) the black blowfly Phormia regina can go from egg to pupa in 150–266 hours (6 to 11 days). When the third stage is complete the pupa will leave the corpse and burrow into the ground, emerging as an adult 7 to 14 days later.
There are 1,100 known species of blowflies, with 228 species in the Neotropics, and a large number of species in Africa and Southern Europe. The most common area to find Calliphoridae species are in the countries of India, Japan, Central America and Southern United States.
The typical habitat for blow-flies are temperate to tropical areas that provide a layer of loose, damp soil and litter where larvae may thrive and pupate.
Info:
http://en.wikipedia.org/wiki/Calliphoridae
