STOMOXYS 609 



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 moon- 

 light 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, Geoffrey. 



[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 



FIG. 421. The stinging fly (Stomoxys calcitrans, Linn.). 



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. 



[One < syz\ts(StorH,oxyscalcitranSi Linnaeus) 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 n mm. long. The pupal stage is passed in the old larva 



