T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Fly (House) Musca domestica

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Suborder: Brachycera
Infraorder: Muscomorpha
Section: Schizophora
Subsection: Calyptratae
Superfamily: Muscoidea
Subfamily: Muscinae
Tribe: Muscini
Genus: Musca
Species: M. domestica
Binomial name: Musca domestica
Common name: Common house fly

This common fly originated on the steppes of central Asia but now occurs on all inhabited continents, in all climates from tropical to temperate, and in a variety of environments ranging from rural to urban. The adults are 8–12 mm long. The females are slightly larger than the males and have a much larger space between their red compound eyes. Houseflies have only one pair of wings; the hind pair is reduced to small halteres that aid in flight stability.
Each female fly can lay approximately 500 eggs and within a day, larvae (maggots) hatch from the eggs; they live and feed in (usually dead and decaying) organic material, such as garbage or faeces.  They live at least one week. They then crawl to a dry cool place and transform into pupae, coloured reddish or brown and about 8 mm long. 
The adult flies then emerge from the pupae. The adults live from two weeks to a month. Houseflies feed on faeces and moist decaying organic matter such as spoiled food, eggs and flesh. Houseflies can take in only liquid foods. They spit out saliva on solid foods to predigest it and then suck it back in. They also regurgitate partly digested matter and pass it again to the abdomen.  They have a keen sense of smell. 
Although this fly species does not bite, the control of Musca domestica is vital to human health and comfort in many areas of the world. They have the potential to transmission pathogens (viruses, bacteria, fungi, protozoa, and nematodes).  Pathogenic organisms are picked up by flies from garbage, sewage and other sources of filth, and then transferred on their mouthparts, through their vomitus, faeces and contaminated external body parts to human and animal food.  Around the world,  the pathogens commonly transmitted by house flies are Salmonella, Shigella, Campylobacter, Escherichia, Enterococcus, Chlamydia, and many other species that cause illness. These flies are most commonly linked to outbreaks of diarrhoea and shigellosis but also are implicated in the transmission of food poisoning, typhoid fever, dysentery, tuberculosis, anthrax, ophthalmia, and parasitic worms.

Parts of a fly (key below graphic)

Key:  I: head; II: thorax III: abdomen. — 1: prescutum; 2: anterior spiracle; 3: scutum; 4: basicosta; 5: calypters; 6: scutellum; 7: wing vein; 8: wing; 9: abdominal segment; 10: haltere; 11: posterior spiracle; 12: femur; 13: tibia; 14: spur; 15: tarsus; 16: propleuron; 17: prosternum; 18: mesopleuron; 19: mesosternum; 20: metapleuron; 21: metasternum; 22: compound eye; 23: arista; 24: antenna; 25: maxilary palps; 26: labium; 27: labellum; 28: pseudotracheae; 29: tip.

Head of a house fly.

A newly emerged fly needs to spend some time inflating its wings with blood and letting them dry before flying.

This photo has the fly with sponging mouthparts extended.  It consists of a fleshy, elbowed labium, at the distal end of there is a large, sponge-like organ called a labellum. The labella is a complex structure consisting of many grooves, called pseudotrachea, which sops up liquids.  Salivary secretions from the labella assist in dissolving and collecting food particles so that they may be more easily taken up by the pseudotrachea.  The liquid food is then drawn up from the pseudotrachea through the food channel into the oesophagus. 

Mating: Under favourable conditions, females become receptive approximately 36 hours after emergence. Most female house flies mate once, storing sperm in their spermathecae to be used later to fertilize eggs for 3 or more weeks. During the process of copulation, the wings of the highly promiscuous males can sometimes quickly become frayed as a result of vigorous action by females resisting their attention.

Thanks to Wikipedia for text and information http://creativecommons.org/licenses/by-sa/3.0/