268 GLOSSINA PALPALIS [CH. 



an hour and a half, but depends to some extent on the sur- 

 roundings. If the ground is soft and dry the larva very soon 

 comes to rest and often pupates within half-an-hour, whereas 

 in hard or damp soil it may be unable to find a suitable place 

 for some little time. In any case, the larva ceases to move after 

 a comparatively short period of active life and then pupates. 



The pupa is of the usual cylindrical form, but at its posterior 

 extremity, it bears the two caudal protuberances that are 

 present in the larva. It darkens rapidly after its formation 

 and within four hours becomes dark brown in colour. The 

 dimensions of the pupa are 6\5 to 6'6 mm. in length by 3*5 mm. 

 in diameter. 



Fig. 71. Glossina palpalis. Puparia before and after the escape of the 

 imago, (x/j). (After Newstead.) 



The duration of the pupal stage depends mainly on the 

 temperature, and may vary from 17 to 72 days. In the 

 laboratory pupae kept at 25-27 C. hatch out in from 

 32 to 33 days, but at slightly lower temperatures Brumpt 

 found that the nymphal period lasted from six to seven weeks. 

 The optimum temperature is probably about 27 C., for 

 Roubaud found that pupae exposed to higher temperatures 

 either did not hatch, or produced unhealthy flies. If placed 

 in damp sand the pupae are soon killed, and immersion in water, 

 for periods exceeding 24 hours, is also fatal. Moreover, a pupa 

 exposed to the action of the sun's rays for four hours on two 

 successive days, failed to hatch, although protected throughout 

 the experiment by a layer of earth 5 cms. in thickness. 



Breeding localities. In 1906 pupae of G. palpalis were 

 discovered by Bagshawe on the shore of Lake George and 

 subsequently on the shores of Lake Albert and the Victoria 



