BLACK FLY, a gnat of the species of the genus Simulium, the common blackfly of northern New England, Canada and Labrador probably being S. molestum. In this tormenter of travelers and fishermen the body is short and thick, the labrum is free, sharp as a dagger, and the proboscis is well developed and draws blood profusely. It is black, with a broad.sil very ring on the legs. The species are numerous.
The cylindrical larva is furnished with short antenna, and near the mouth are two flabelli f orm appendages. The pupa has eight very long lateral filaments on the front of the thorax, and the posterior end of the body is enclosed in a semi-oval membranous cocoon, open in front, and posteriorly attached to some submerged plant such as eel-grass. The fly leaves the pupa beneath the water. She deposits her eggs on the rocks in a compact layer a few inches above the surface of the water. The eggs of the Hungarian or midge" are enveloped in a yellowish-white slime and deposited at the end of May or early in June upon stones or grass over which water flows, or in the brooks of the more elevated regions. The num ber laid is variously estimated at from 500 to 5,000. The food of the larva of the buffalo gnat has been proved to be carnivorous, and it is supposed that the larva of all the species live on animal matter, though possibly in some cases on dead leaves. On hatching the larva become attached to plants, etc., or to each
other, by a silken thread, forming long floating strings. When the fly issues from the sub merged pupa-case she rises to the surface, then being protected by a fine silky covering of hairs. The adult fly in central New York issues about the first of April, and those apparently of a new brood the first of June; after this there is a succession of generations throughout the season; the development of a single brood occupying about two months. The larva hiber nates.
While the black fly of Maine, and presum ably of Labrador, is of the species S. molestum, that of the Saint Lawrence Valley has been named S. invenustum, and is said to be differ ent from that of Lake Superior. A remarkably large species is known as S. pictipes; its larva and pupa were found in the rapids of the Au Sable River, and also similar ones on the north shore of Lake Superior.
The black fly is mostly active in the bright sunlight, generally disappearing on cloudy days, but it is known to crawl under one's clothes and to bite in the night. The bite is often severe, the creature leaving a large clot of blood behind it. The best preventive is oil of tar, and the use of various ointments. Consult Bulletin No. 10, Division of Entomology, United States Department of Agriculture (Washington 1898).