26 Guide to Insects and Ticks 



form of sleeping sickness caused by Tnjpanosoma rhodcsiensc 

 Stephens and Fantham. This species of tsetse-fly is usually 

 confined to definite tracts of country, known as " fly-belts," often 

 of very limited extent. Unlike G. palpalis, G. morsitans is not 

 confined to the immediate vicinity of water. The female deposits 

 its maggot or larva in hollows about the roots of trees, and not in 

 the soil under bushes, where it might be found by the scratching 

 of guinea-fowl and other birds in search of food. Some empty 

 pupa-cases are shown. 



In the larger of the two glass vessels are specimens of tsetse- 

 flies (Glossina palpalis, G. morsitans and G. tachinoides) before 

 and after a full meal, showing the extent to which the abdomen 

 can be distended with blood. Tsetse-flies are dependent for their 

 continued existence upon the blood of vertebrate animals, including 

 man, wild and domesticated mammals, birds and reptiles. Contrary 

 to what is the case in the majority of blood-sucking flies, such as 

 mosquitoes and horse-flies, in which the females alone suck blood, 

 in tsetse-flies the habit is common to both sexes. The amount of 

 blood imbibed at one meal is relatively considerable, the fly's 

 abdomen originally empty and flat becoming swollen out like a 

 bead in consequence. 



The tsetse-flies on the second panel are examples of species 

 which have not been proved to convey sleeping sickness to man, 

 though many, if not all, are concerned in the dissemination of 

 trypanosomiasis among domestic animals. The species exhibited 

 are: Glossina caiiijincti Austen, G. palliccra Bigot, G. tachinoidcs 

 Westw., G. imllitUjH's Austen, G. longipalpis Wied., G. austcni 

 Newst., G. fusca Walk., G. niyrofusca Newst., G. brevipalpis 

 Newst., G. mcdicorum Austen, and (/. It m<ii Dennis Corti. 



TABANID FLIES AND "GALA HAH 

 SWELLINGS." 



The disease known as " Calabar swellings," a form of filariasis 



prevalent in West Africa, is caused by thin thread- worms of the 



species /''//////</ (/,"<>) ha Stiles, the larva of which undergoes its 



morphoeifl in the salivary glands of female tabanid flies of 



the # MIUS 



