31 



directly with the relative humidity of the atmosphere, and the author 

 says that he constantly found, on days when there had been a little 

 rain early, followed by the sun shining through the clouds, that the 

 flies were terribly persistent in their attacks ; but on a brilliantly 

 fine windy day they were not nearly so desirous of feeding. There 

 appears to be an inverse relation between the number of flies and the 

 temperature, but this will be influenced by local conditions affecting 

 relative humidity. He also is of opinion that there is an inverse 

 relation between the proportion of feinales and the temperature, and 

 suggests that the females are more susceptible to heat, which may 

 account for the much smaller proportion of females on the islands 

 where the temperature is higher. From figures representing the 

 number of pupae captured in the same localities by the same fly boys 

 it seems that there is an intimate relationship between the number of 

 larvae deposited and the relative humidity. 



Seeing that the rate of reproduction of Glossina is abnormally low 

 for an insect, in that it brings forth only one offspring at a time and 

 only a total of a dozen or so, there is, the author thinks, strong a priori 

 evidence against any great destruction of Glossina taking place by the 

 attacks of enemies : and during 2| years in which he had been studying 

 the subject he did not succeed in finding any enemies of importance. 

 No parasites were reared from the many thousands of pupae which 

 were kept in closely shut boxes with glass lids : and although pupae 

 were destroyed by an Acarid, it was also found that the same Acarid 

 attacked pinned insects, and it is possible that the pupae attacked were 

 alreadv dead. Neither had the author, except on one occasion, found 

 any insect attacking the newly emerged fly. He also regards it as 

 improbable that this Glossina is attacked by birds, inasmuch as it 

 frec|uents bush or forest with thick undergrowth, thus keeping out of 

 the way of the larger insectivorous birds of powerful flight which would 

 alone be capable of catching such an active insect. Results of the 

 examination of the stomachs of 64 insectivorous birds shot while feeding 

 on the fly-areas of Damba and Bugalla Islands tended to show- 

 that no Glossina had been consumed. A very abundant species of 

 dragon fly {Cacergates leucosticia) has been seen to catch and devour 

 Glossina. Fhes of the family Asilidae have been carefully watched 

 and on only one occasion was Glossina seen to be captured by one. 

 Nematodes have been found in the abdominal cavity of \ out of I.OOO 

 flies. 



The next question the author considers is the food supply of 

 Glossina ; the sources from which it derives blood, and the question 

 as to whether it feeds on vegetable juices or no, and whether it sucks 

 up water. In answer to the first question a table is given showing the 

 proportion of mammalian (M) and non-mammalian blood (N) found 

 in the flies in three different localities : -linja (mainland), M. 3r5' per 

 cent., N. 68'5 per cent. ; Damba Is., M. 15'2 per cent., N. 84*8 per 

 cent. ; Bugalla Is., M. 68"7 per cent., N. 31'3 per cent. : but these 

 proportions varied greatly from day to day. It was found that 4 per 

 cent, of the non-mammalian blood in a large ]iumber of flies examined 

 could be described as avian, and 95" 7 per cent, as reptilian, the latter 

 being probably derived chiefly from monitor lizards. Amphibian or 

 ophidian blood was never found. Tlie question whether Glossina 

 feeds on vegetable juices is a difficult one to answer definitely, though 



