House Fly

Musca Domestica

Appearance Egg: The white egg, about 1.2 mm in length, is laid in small groups. Larva: The mature larva is 3 to 9 mm long, typical creamy whitish in colour, cylindrical but tapering toward the head. The head contains one pair of dark hooks. The posterior spiracles are slightly raised and the spiracular openings are sinuous slits which are completely surrounded by an oval black border. The legless maggots emerges from the egg in warm weather within eight to 20 hours, and immediately feeds on and develop in the material in which the egg was laid. The full-grown maggot has a greasy, cream-colored appearance and is 8 to 12 mm long.

The larva goes through three instars. When the maggot is full-grown, it can crawl up to 50 feet to a dried, cool place near breeding material and transform to the pupal stage. High-moisture manure favours the survival of the house fly larva.

Pupa: The pupa is dark brown and 8 mm long. The pupal stage is passed in a pupal case formed from the last larval skin which varies in colour from yellow, red, brown, to black as the pupa ages.

Adult: The house fly is 6 to 8mm long, with the female usually larger than the male. Its head has reddish-eyes and sponging mouthparts. The thorax bears four narrow black stripes and there is a sharp upward bend in the fourth longitudinal wing vein. The abdomen is gray or yellowish with dark midline and irregular dark markings on the sides. The underside of the male is yellowish. The sexes can be readily separated by noting the space between the eyes, which in females is almost twice as broad as in males.

Feeding Habits

House flies can only ingest liquid food. Solid food may be consumed by first liquefying it with regurgitated saliva which is then sponged up with the proboscis.

Lifecycle

Each female fly will lay batches of 75 to 150 eggs over a three to four day period. The number of eggs produced is a function of female size which, itself, is principally a result of larval nutrition. The average number of eggs is about 500. Eggs are laid in warm, moist, organic materials such as manure, garbage, lawn clippings or decaying vegetables and fruits. Young larvae respond to light byl burrowing into the organic material in which they are developing. Older larvae respond positively to light and will emerge from their organic habitat to seek drier and cooler areas to transform into pupae.vDevelopment from egg to adult can be completed in as little as 7 days. As many as 10 to 12 generations may occur in one summer.

Disease

Flies regurgitate and excrete wherever they come to rest and thereby transmit disease organisms. Pathogenic organisms are picked up by flies from garbage, sewage and other sources of filth, and then transferred on their mouthparts, through their vomitus, feces and contaminated external body parts to human and animal food.

More than 65 pathogens are associated with the house fly which may cause disease in humans alone.

Blow flies are known to carry bacteria and viruses that cause conditions such as diarrhoea, typhoid fever (Eberthella typhosa), bacillary dysentery (Shigella dysentariae), tuberculosis, anthrax ophthalmia and infantile diarrhoea, as well as parasitic worms, cholera (Vibrio comma), poliomyelitis, food poisoning, yaws, tularaemia, and eye infections. They have also been suspected as vectors of the viral agent that causes poliomyelitis. Food preparation and storage areas can be contaminated by the flies themselves or their faeces.