50 NATURAL HISTORY OF GLOSSINA PALPALIS 



Accordingly I made some efforts to obtain the larvae 

 from pregnant flies captured when the larva was far 

 advanced in growth and kept in a cage, fed at regular 

 intervals, until the larva had been extruded. But 

 premature expulsion of the larva, ending in its death, 

 took place so often that the attempt was given up. 



The next opportunity afforded to enemies is the brief 

 moment after the larva has been extruded and is scramb- 

 ling over the surface of the sand in the endeavour to find 

 a spot where it can penetrate and hide itself. I have 

 watched this happen ; the birth of the larva in the eight 

 cases witnessed took place between 10' 45 a.m. and 1 p.m. 

 It is very active, but being white with black bosses 

 at the posterior extremity, is quite conspicuous as it 

 wriggles over the surface. On several occasions I have 

 placed the larva in front of a species of ant, Paltoihyreus 

 tarsatus, and seen the ant pick up the larva, give 

 it several nips with its large mandibles, and carry it 

 off. Once, on arrival at the breeding ground, among 

 some bushes where I used to lie and watch for events, 

 I saw one of these ants wandering about with a larva 

 in its mandibles. 



This ant was very often seen on the beaches where the 

 fly breeds, wandering about and evidently searching for 

 food, and no doubt it does occasionally destroy a larva, 

 as was once seen. But it cannot often enough happen 

 to meet a larva before it disappears into the ground to 

 be of value as a controller of the numbers of the fly. Birds 

 also may occasionally pick up the larva while it is thus 

 exposed, but it can only happen rarely. 



The greatest destruction of Glossina by enemies probably 

 takes place during the several weeks that it lies just below 

 the surface of the soil as an inert pupa, but I have obtained 

 no evidence of any vertebrate enemy. No traces have 

 ever been seen on a breeding ground such as would be 

 left by a bird scratching the surface as do game birds. 



