THE WILD FAUNA OF THE EMPIRE 15 



ignore facts, and it must be regretfully admitted that not a particle 

 of evidence exists to show that any species of the genus Glo^sina 

 can support itself upon diet of a vegetarian character. For my 

 own part, at any rate, after a fairly close study of the subject 

 during the past six years, I am convinced that no species of tsetse 

 can continue to exist without blood of some kind; but, as will 

 shortly be shown, it does not at all follow that the blood mnst 

 necessarily he mammalian. As regards the need for blood in some 

 form, however, abundant proof is to be found in the records of 

 recent experiments to test the capacity of tsetse-flies to transmit 

 the parasite of sleeping sickness. Thus Dr. J. L. Todd, writing 

 of captive specimens of Glossiyia palpalis in the Congo Free State, 

 used for experimental. purposes by the expedition of the Liverpool 

 School of Tropical Medicine to the Congo, 1903-5, says : ' If they 

 were left without an opportunity to feed [on blood] for much more 

 than 24 hours they died very quickly, about 91 per cent, in 

 37 hours. Neither sex seemed particularly resistent.'' Again, 

 Dr. P. H. Ross, after experimenting in British East Africa wdth 

 other species of tsetse-flies {Glossina fusca, G. longipe7inis, and 

 G. pallidipes), which were fed on monkeys, states that ' It was 

 found that if the period of starvation were prolonged beyond four 

 days very few flies survived. ' - In I^ganda members of tlie Sleeping 

 Sickness Commission state with regard to Glossina palpalis that 

 they were ' never able to obtain any definite proof that it fed on 

 anything but blood. ' ^ 



It is true that many species of Diptera (two-winged flies), 

 belonging to groups notorious for their blood-sucking propensities, 

 may exist in the adult state and even reproduce their kind without 

 tasting blood. Not to mention the mosquitoes, among which a 

 number of instances in support of this statement might be found, 

 illustrations are provided by the Tabanidae (horse-flies, clegs, 

 serut-flies, &c.), two species of which, it may be remarked, have 

 recently been shown by the brothers Sergent to be capable of con- 

 veying a trypanosomiasis (El Dehab), which decimates drome- 

 daries in Algeria. According to Hine,'* the females of some 

 American Tabanidae take other food than blood, and the author in 

 question expresses the belief that it would not be ' overstating the 

 facts to say that specimens of this sex may pass the period of 

 adult life without taking blood at all.' Hine states that he has 

 often seen both sexes sipping dew from leaves, and has observed 

 a number of species of Chrysops and Tahaniis, belonging to both 

 sexes, feeding on the honeydew produced by aphides. These state- 



1 Annals of Tropical Medicine and Parasitology, vol. i. No. I. (February 1, 

 1907). V. 70. ■ 



- 'Reports of the Sleepin2: Sickness Commission of the Royal Society,' 

 No. VIII. (February 1907\ p. 81. 



■^ Minchin, Gray, and Tullocb, ihid. p. 131. 



4 U.S. Department of Agriculture, Miscellaneous Papers, 1906. p. 25. 



