[This species is confined to “belts,” often of very limited extent, and appears to prefer regions where there is sufficient vegetation for moderate but not excessive cover and a hot, moderately dry climate. It is not nearly so dependent upon water as is G. palpalis, and generally is most active in a dry atmosphere; some observers, however, state that in certain districts it is more common along the banks and edges of rivers. This tsetse-fly has been taken as high as 5,500 ft. altitude. It infests native villages as well as the bush. Like other tsetse-flies it bites not only during the hottest part of the day, but also on bright warm moonlight nights, and it feeds on the blood of all mammals.
[The structure of the male genitalia of those representatives of G. morsitans occurring on the West Coast of Africa and in parts of the Soudan presents certain constant differences from that of the typical form of this species; this form is known as G. morsitans, race submorsitans, Newst.
Genus. Stomoxys, Geoffroy.
[The members of this genus which occur in temperate and tropical countries are provided with a hard, slender, shiny black proboscis which projects horizontally from beneath the head; by means of this structure they can bite severely. In general appearance they resemble house flies, but the proboscis at once distinguishes them. In many parts of Britain they are known as storm flies on account of their frequent appearance indoors previous to a storm of rain or wind, which I have invariably found to be correct; they are also called stinging flies. In colour they are greyish, dusky or brownish-grey or black, varying from 5 to 7 mm. in length; the thorax has dark longitudinal stripes and the abdomen dark spots or bands. In the male the eyes are closer together than in the female. These flies usually occur in stables and farmyards, along woods and in lanes, and mainly attack mammals.
Fig. 421.—The stinging fly (Stomoxys calcitrans, Linn.).
[One species (Stomoxys calcitrans, Linnæus) occurs practically all over the world. The female lays her eggs in moist, warm, decaying vegetation; as many as eighty may be laid by a single female. The ova are white, banana-shaped, with a broad groove on the shorter curvature; they may hatch in two or three days. The creamy-white larva tapers to a point at the head end, and is truncated at the tail end. Two black mouth hooks are plainly visible at the cephalic extremity. There are two plates on the posterior surface of the last segment which bear the respiratory pores, nearly circular in outline. It reaches maturity in fourteen to twenty-one days; when mature it is 11 mm. long. The pupal stage is passed in the old larva skin and lasts from nine to thirteen days; it is barrel-shaped, 5 to 8 mm. long, and of a bright reddish-brown to dark chestnut-brown colour.
[This insect may act as a carrier of anthrax, and has been proved to be the agent of an extensive epidemic of malignant pustule in the Isle of Pines, New Caledonia.[425]
[Noè’s[426] experiments tend to show that it is an intermediate host and transmitter of Filaria labiato-papillosa of the ox.