WERNER MARCHAND 169 



The eggs (Plate 1, Figs. 8 and 9) are placed by the female fly on the 

 upper side of a blade of grass or some similar plant, and, with the excep- 

 tion of the single batch taken at Kanissa wood-station, all those found 

 were overhanging water. An unfinished batch of eggs resembles an 

 arrow-head. The eggs are closely applied to each other and left bare, 

 so the batch can easily be seen when freshly laid, owing to its shin- 

 ing white to yellowish white color. Prior to hatching, the egg mass 

 becomes darker. According to King, "the egg is spindle-shaped, 

 about 1.75 mm. in length and, when first laid, is white in colour. 

 It becomes darker as the embryo within develops." 



The eggs obtained in the breeding cage were laid on May 24 to 25, 

 and hatched on May 29. This would correspond to the very short 

 incubation period of four to five days. The larvae (Plate 1, Fig. 9, a) 

 were placed in glass basins containing mud, growing grass, and water, 

 and were offered the expressed stomach contents of female ticks — 

 Rhipicephalus simus — taken from a dog. They fed readily on this 

 until June 1 1, when they were placed in clean river sand and water, and 

 their diet was changed to mosquito larvae. These mosquito larvae 

 were either killed or laid living on the wet sand out of reach of the 

 water, in which position the tabanid larvae were able to kill them. 

 In water the mosquito larvae were too active to be caught. On July 

 16 their food was changed again to freshly killed and bruised earth- 

 worms, and these they also ate readily. While still young they be- 

 came vicious cannibals, and consequently each larva had to be given 

 a separate dish. They were brought to Khartoum on July 19 and a 

 few days later it was noticed that the majority were not taking their 

 food. They were then nearly if not quite full grown, so it was thought 

 that they had buried themselves in the sand prior to pupating. A 

 thorough search, however, revealed the fact that they had disappeared, 

 and it was not until later that mice were identified as the cause of the 

 loss. The two remaining larvae were then killed and preserved. It 

 is possible, therefore, that the larva described by King is not quite 

 mature. 



The larvae of Tahanus tcEuiola are more active and ferocious than 

 those of Tahanus par, vigorously attacking any other larva with 

 which they may come in contact. They have not, however, the 

 power possessed by Tabanus par of lying dormant in the soil for at 



