It is one of the most common insects on earth. It is found in almost every corner of the planet. The housefly is thought to have originated in areas of the Middle East in the early Cenozoic, which began 66 million years ago and continues to this day. Across the globe, the housefly has spread through migration and human colonization.
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It is probably the most widespread insect in the world.
It is found in all populated parts of Europe, Asia, Africa, Australasia and the Americas, in the Arctic and in tropical equatorial forests, where it is widespread.
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The house fly is a small insect, reaching a size of 6 to 7 mm.
The wingspan is 13 to 15 mm. The female fly is larger than the male.
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Each leg ends in a pair of claws and pulvilli.
The pulvilli is an adhesive tab that allows the fly to move along walls using Van der Waals forces. This effect is based on the mutual attraction of electrons and nuclei in molecules, specifically between the permanent dipole and the induced dipole induced by the molecules that build the adhesions.
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The thorax of a housefly is dark gray and covered with darker stripes.
The underside of the body is lighter than the top.
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Flies have a liquid diet adapted mouthparts.
It is used to ingest liquids and the solid fraction previously dissolved with saliva.
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The eyes of flies provide a 360° field of vision.
They are brownish-reddish in color, compound and consist of about four thousand ommatidia.
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They are mainly carnivorous and feed on decaying organic matter.
Both adults and larvae can be found on decaying vegetables, fruits, meat, and plant secretions. Adults also feed on the nectar of flowers. Solid food is softened with saliva before being aspirated.
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Houseflies play an important ecological role in the decomposition and processing of organic matter.
By feeding on feces and carrion, flies contribute to faster decomposition.
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Flies flap their wings about 200 times per minute during flight.
Average housefly speed is about 8 kph.
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Because of their ectothermic nature, they are most active in warm conditions.
The search for warmth explains why flies so eagerly seek shelter in human dwellings. 12 generations may hatch in temperate regions per year; in the tropics and subtropics, more than 20.
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The female lays about one hundred eggs in a single batch.
The laying process can take several days, and over a lifetime, a female housefly can lay up to 2,000 eggs, although this number does not usually exceed 500.
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Housefly eggs are about 2.5 mm in diameter.
They are most commonly laid in pig feces, where up to 15,000 larvae may hatch in one kilogram of a substrate. After 24 hours, the larvae hatch from the eggs and feed on the liquid fraction of the substrate. The quality and freshness of the substrate affect the growth rate of these insects.
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Fly larvae are called maggots.
They are white, legless organisms that feed on organic material at their hatching site. After hatching, they avoid light. Larval development takes two weeks under optimal conditions to 30 days or more in a cooler environment.
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The housefly larva goes through three stages of development.
At the end of the third stage, the larvae crawl to a dry, cool place and develop into pupae. The pupa has a cylindrical shape with rounded ends. It reaches a length of about 1.2 mm and consists of the last stripped skin of the larva. At first, it is yellowish, darkens with time, and becomes practically black with red and brown tint.
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The metamorphosis of the pupa at 35 °C lasts from two to six days.
At 14 °C, metamorphosis may take more than twenty days. After hatching from the cocoon, the fly stops growing and reaches its maximum size. A housefly pupa weighs between 8 and 20 milligrams.
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The size of a fly is not an indication of its age.
Whether a fly is large or small only indicates whether the insect fed adequately during the larval stage.
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Adult houseflies live from two weeks to one month.
Individuals reared under laboratory conditions live even longer. Males reach sexual maturity 16 hours after hatching and females after 24 hours.
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When conditions are optimal, the life cycle of a fly may be completed within seven to ten days after hatching.
Under less favorable conditions, it can take up to two months.
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They are the prey of many animals.
They constitute a significant meal for birds, reptiles, amphibians, spiders, and other insects. In turn, eggs, larvae, and pupae are usually threatened by parasitism.
Histeridae beetles feed on fly larvae and some mites larvae such as Macrocheles muscaedomesticae feed on fly eggs. A single larva is capable of eating 20 of these per day.
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Flies are a transmission vector for over 100 pathogens.
Because they can travel up to several miles from their breeding sites, they spread various diseases and parasites found on fly body hairs, mouthparts, vomit, and feces. The pathogens spread by flies cause typhoid fever, cholera, salmonellosis, dysentery, tuberculosis, anthrax, and ocular inflammation.
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Flies as biological weapons were used during World War II.
The Japanese, under the leadership of Shirō Ishii, worked on entomological warfare techniques. They constructed bombs that contained two chambers. The first was filled with houseflies, the second with a bacterial suspension of the cholera pathogen (Vibrio cholerae) that causes cholera. The flies were coated with the suspension when the bomb was dropped and then released.
The first such bomb was dropped in 1942 on the Chinese city of Baoshan, where the Allies were stationed. Initially, the bomb killed 60,000 people, then the disease spread in a radius of 200 kilometers and claimed 200,000 victims. In 1943, another bomb was dropped on Shandong, where the epidemic killed 210,000 people.
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Fly larvae are collected or raised as fodder for livestock.
