24 MODE OF REPKODUCTION 



reader, after what has been stated in the preceding paragraph, 

 to learn that the Tsetse has a totally different life-history, albeit 

 the details of the process are even more exceptional than could 

 have been anticipated. 



According to Colonel Bruce : * " The Tsetse-fly does not lay 

 eggs as do the majority of the Diptera, but extrudes a yellow- 

 coloured larva nearly as large as the abdomen of the mother. 

 This larva is furnished with a black hood at one pole and two 

 minute spikes at the other. It is annulated and consists of ten 

 segments. Immediately on being box'n the larva creeps about 

 with a good deal of activity, evidently searching for some cover 

 or hole in which to hide. Having found a resting-place, it imme- 

 diately begins to change colour, and after a few hours has turned 

 into a jet-black hard pupa or nympha. 



" If these pupal cases are placed in a perfectly dry place, as 

 in a wooden box, the perfect insect hatches out in about six 

 weeks. From this it would appear that the life-history of this 

 species of fly is very simple, it only being necessary for the female 

 insect to deposit the larva on the surface of the soil or in the 



f grass, M'hen the larva creeps into the nearest shelter, in a few 

 hours becomes hard and black, and in five or six weeks hatches 



/ put into the fully-developed Tsetse-fly. It has often been sur- 

 jpised that this fly is bred in buffalo-dung, but from a consideration 

 of the foregoing facts it is evident that nothing is wanted except 

 any moderately dry place." 



Such are the details of the life-history of the Tsetse as pre- 

 sented by Colonel Bruce, and it will at once be perceived by 

 those who know anything of the metamorphosis of Diptera iu 

 general that they exhibit a remarkable similarity to what takes 

 place in the group of parasitic flies which, on account of their 

 peculiar mode of reproduction, have been termed Pupipara.f 



of the house-fly {Musca domcstica, Linn.), which it much resembles. 

 Lyperosia irritans, Linn., is said to breed in cow-dung. [Cf. "Insect 

 Life," Vol. II. (1889), p. 97) : in the paper referred to, the species is called 

 Ha&matohia serrata, Rob.-Desv.). 



* Cf. Chapter VII., Appendix A, p. 271. 



t Of these the best known are the mammal- and bird-parasites belonging 

 to the family Hippoboscidse (genera Hippobosca, Ornithomyia, Stenopteryx, 

 Oxyptcrum, Lipoptena, and Melophagus). Hippobosca equina, Linn., is a 

 weil-ljnown plague of horses and cattle in the New Forest ; other species 

 occur in Africa and India, and are found on horses, cattle, camels, and 

 dogs; the genus Ornithomyia includes a number of species, all of which 

 are parasitic on various kinds of birds; Stoioptcryx hirundinis, Linn., 

 is found on the martin (Chelidon urbica, Linn.), Oxypterum pallidum, 

 Leach, on the swift (Cypselus apus, Linn.) ; Lipoptena cervi, Linn., is 

 paras.itic on the r^d- and roe-deer, while Melophagus ovinus, Linn., is the 



