Fly Facts

Fly, the common name of many insects belonging to various genera and species, and characterized in general by two transparent wings. Some flies, however, have no fully developed wings. In almost all the species, even in those which have no full-grown wings, there are present two small rod-like organs which take the place of the hind wings and probably serve as balancers in flight. Besides the flies there is only one other insect, a scale-insect, which has but two wings. The head of a fly is usually insignificant, except for the eyes, which are relatively very large and consist often of thousands of facets. There have been, over 40,000 species of flies described. But it is believed by prominent scientists that there are at least four times this number of species, and some place the number as high as 350,000. The difficulties in the way of studying the Diptera or flies, are great, as the insects are very frail and satisfactory specimens are hard to prepare.

The midges, gnats, mosquitoes and fleas all belong to the Diptera, but in common language the word fly is often applied to insects which are not strictly Diptera, or true flies, as for example, the dragon fly and the May fly. The house fly is the most common of the Diptera. Wherever man is, the house fly is found, and in hot weather it causes a great deal of annoyance. It is furnished with a sucking apparatus, through which a fluid may be poured to soften hard substances. It can climb the smoothest surfaces, and even walk on a ceiling, because of the sucker-like hairs which grow on its feet.

The female lays her eggs in rotting refuse or in the manure of a barnyard, and the larvae, which hatch in a few hours, are small white maggots, which change into pupae without casting their skins and in from eight to fourteen days become mature flies. As each fly lays more than one hundred eggs, and a new generation can be produced in ten days, it is evident that the increase is astonishingly rapid. A few flies survive the winter in sheltered places and so preserve the species, though it is probable that many of the pupae live through the winter. Flies are undoubtedly a source of contagion and an important factor in the distribution of disease. Not only do they gather the germs in the decaying matter where they lay their eggs and transport them by their bites into the human body, but by crawling over food they may leave the germs to be taken into the stomach. In Egypt and some of the Eastern countries, where the religion of the people prevents them from killing any insect, the flies carry the germs of ophthalmia from one person to another till it is unusual to find an adult human being with perfect eyes.

Anthrax and other diseases are communicated among animals by flies, and it is thought that typhoid fever also is distributed in this way. It is very evident that flies should be excluded from the house wherever possible, and a consistent and universal effort to exterminate them would result in diminishing the nuisance very largely.