INSECTS 



175 



Even larger is a species from the Cameruns, in which the thorax is black with 

 rive longitudinal white stripes, while the wing-covers, or elytra, are marked with 

 dark crimson. The genus is peculiar to Ethiopia. 



Most notorious of all Ethiopian insects are the tsetse-flies of the order Diptera, as 

 typified by the South African Glossina morsitans. These flies, which are unknown 

 elsewhere, may be easily recognised when at rest by the circumstance that the 

 wings are folded so as to fit the shape of the body, instead of projecting in 

 two angles, as in ordinary flies. Some interesting notes on the habits of G. 

 palpalis, the tsetse-fly of sleeping sickness, are given in one of the issues of the 

 Bulletin of the Sleeping Sickness Bureau. In common with other tsetses, this 

 species differs from other flies in that the female, in place of laying eggs, extrudes 

 a single yellow larva or grub nearly as large as her own abdomen, and furnished 

 with a black hood at one end and a pair of minute spines at the other. Immedi- 

 ately after birth this grub commences to crawl actively about in search of a suitable 

 shelter in which to pupate, turning, so soon as this is found, into a hard shining 

 black pupa. From the latter the full-fledged 

 tsetse is developed in the course of five or 

 six weeks. In the Lake Region tsetses do 

 not make their appearance abroad till the 

 sun is well above the horizon, their usual 



time on a bright still 



being from 



THE COMMON TSETSE. 



about 7 to 7.30. Where forest-trees keep off 

 the sun's rays for some hours, the insects 

 may not be seen on the wing till 10 a.m., 

 when they may become numerous ; on fine 

 days their numbers begin to diminish from 

 about 4 to 4.30 p.m., and by half an hour 

 before sunset few are to be seen, although 

 in exceptional instances they remain on the 

 wing till the sun has set. 



Though sun seems essential for them to be active, tsetses prefer the shade ; in 

 some districts they appear to become a little sluggish in the heat of the day, at 

 which time their desire to bite seems also to undergo a slight diminution in 

 intensity. Wind drives them to shelter at once ; and on a windy day not one is 

 to be seen in spots where they abound in calm weather. The swift, irregular flight 

 of these flies is familiar to all travellers in the districts they infest; and it cannot 

 be said whence they come or whither they disappear. As a rule, it seems that 

 their approach is almost noiseless ; but, strange to say, there is a certain amount of 

 discrepancy on this point in the accounts of observers. One traveller, for instance, 

 states that the fly's presence may usually be detected by the ear sooner than by 

 the eye, while a second observes that tsetses may be identified by the peculiar 

 buzzing sound they make when on the wing. On the other hand, a third observer 

 states that when tsetses fly quietly their humming is so gentle that it is not always 

 audible even when close to the ear; when, however, they are in wilder flight the 

 humming is loud and accompanied by a sharper undertone. They settle quietly, 

 but by no means always with the intention to bite ; and they may often be seen 



