130 THE EARLY STAGES OF TABANID^ 



cluster. The single egg is "spindle-shaped, about 1.15 mm. in length 

 and white in color, becoming darker as the embryo within develops." 



The eggs obtained hatched on May 30, consequently after an incu- 

 bation period of six to seven days, and the tiny larvae (Plate 1, Fig. 

 11) were divided into three lots, and placed in glass basins containing 

 mud, water, and growing grass. These basins for purposes of refer- 

 ence were labelled A, B, and C. At the time when the eggs hatched, 

 King was in the Sudan region, where it was impossible to land and 

 obtain any subterraneous insect larvae or tiny fresh water crustaceans 

 for them, so they were offered the expressed stomach contents of 

 gorged female ticks — Rhipicephalus simus — taken from a dog. A 

 few fed once or twice but the majority refused, and all buried them- 

 selves in the mud. 



On June 11, the larvae from A were transferred from mud to clean 

 river sand and water, and given freshly killed mosquito larvae. They 

 fed on these readily and grew apace, though at greatly varying rates. 



The larvae in B were also given mosquito larvae from June 11, but 

 they refused to feed, and the mud in which they were living was sev- 

 eral times allowed to dry up. On July 11 they were placed in clean 

 river sand and water, and at once began to feed and grow. 



On July 19, when King returned to Khartoum, their diet was 

 changed, owing to the difficulty of obtaining mosquito larvae, to 

 freshly killed and bruised earthworms. They did not take readily 

 to this food, and some died, while others disappeared from the basins. 

 At the time it was thought that they had begome cannibals, but 

 eventually it was found that they were being taken by mice. The 

 stock of larvae from A and B had by this time become reduced to 

 one, which appeared to be full grown and so was killed and preserved. 



On July 26 the larvae from C were transferred to clean river sand 

 and water. It was then fifty-seven days since they had emerged 

 from eggs, and they had spent a great part of that time in a dry 

 cake of mud. Occasionally this mud had been moistened, and food 

 offered them, but they had very rarely taken it. Most of them were 

 alive, but with the exception of a few which were slightly larger than 

 when just hatched, they had not grown at all. They now under 

 more favorable conditions fed readily on a mixed diet of earthworms 

 and mosquito larvae and grew, some rapidly, others more slowly. 



