88 



quite sure even then that they did drink, though I thought I saw one 

 or two do so. 



" I have endeavoured to test also whether flies ever drink dew, and 

 whether they will feed on various fruit juices, saline solution, etc., 

 but have not obtained any positive results." 



After experience gained by studying G. brevipalpis, G. morsitans 

 and G. pallipides in Portuguese East Africa, Swynnerton writes (145) : 

 " My flies frequently applied their proboscides to grass-stems put into 

 the tube wet (to simulate the effect of dew), never to those inserted dry. 

 My native informants on the Umvuazi agreed in asserting that they 

 frequently saw tsetses in numbers ' drinking ' on the wet sand of the. 

 river in very hot weather. I have watched Tabanus on the wet mud 

 of pig wallows at the Amanzimhlope head-waters with its proboscis in 

 definite contact with the moisture, as were those of non-biting Muscid 

 flies of several species that were also present, and this habit of drinking 

 is a common one in hot weather on the part of both Diptera and 

 butterflies. Kinghorn and Lloyd have both noticed tsetses at the edges 

 of puddles ; Moiser obtained records of it from his natives, and saw his 

 captive flies insert their proboscides into the wet soil of their bottles ; 

 and Lloyd obtained the same result from moistened sponge and 

 moistened blotting paper that I obtained from wet grass. Carpenter 

 has gone further, for he has traced the presence of the liquid inside the 

 fly. The point is not merely of importance in relation to the hot- 

 weather needs of the fly ; it may also be important, it seems to me, in 

 relation to the possibility of poisoning the highly localised male swarms 

 of G. morsitans by spraying the grass they rest on. 



" Lloyd's positive results from slices of water-melon go to confirm 

 Maugham's observations (under natural conditions) as to the sucking 

 of vegetable juices [cf. also Schwetz's observation of the sucking of 

 leaves of plants by males of G. brevipalpis in North Katanga p. 58]. 

 It is probably moisture rather than real nourishment that would thus 

 be sought and obtained." 



EXPERIMENTS IN FEEDING TSETSE-FLIES WITH EXTRAVASATED 

 BLOOD. In order to feed Tsetse-flies with extravasated blood, Dr. 

 Rodhain and his colleagues of the Mission Scientifique du Katanga 

 (October 1910 to September 1912) devised a small piece of apparatus, 

 very simple yet very ingenious, by aid of which the insects were fed 

 without the slightest difficulty. 



The object was to cause famished Glossina morsitans to bite through 

 a pervious membrane, into blood kept under pressure by force of 

 gravity. 



The following is a description of the apparatus, extracted from the 

 report (116) on the Travaux de la Mission Scientifique du Katanga 

 (Drs. Rodhain, Pons, Van den Branden and Bequaert. See Fig. 8). 



Over the lower orifice of a small glass cylinder, 3 cm. in height by 

 1 cm. in diameter, is stretched a piece of fresh skin of some animal 

 (preferably a mouse or rat, in which the skin is very fine and supple), 

 with the hair outwards. 



Into the upper orifice is fitted, by means of a rubber joint, an ordinary 

 graduated pipette, of the capacity of 1 c.c. and marked in divisions of 

 0-1 c.c. 



The lower cylinder being completely filled with citrated blood, on 

 fitting in the pipette the liquid rises into the latter, to a height which 

 is easily controlled. 



