89 



" The eggs are deposited in a rounded mass on grass and iccds 

 overhanging a pool. One egg mass tliat was counted contained 

 about 450 eggs. The entire act of oviposition was not timed, hut 

 it is a lengthy proceeding, and occupies well over half-an-hour. 

 When a female is ovipositing, although usually exceedingly shy, 

 the stem on which she is resting may be plucked and carried away, 

 or put into a bottle without disturbing her. Having deposited her 

 eggs, she covers the mass ^\dth a creamy-white secretion, which turns 

 black after a short time. 



" The eggs under observation hatched in about eight days, but 

 possibly under natural conditions, exposed to the sun, the incubation 

 period would be shorter. On hatching, the larvae fell into the 

 water, swam to the sides, and buried themselves in the mud. 



" The larvae can only swim on the surface of the water, and 

 progress either by a telescopic movement or by lashing vigorously 

 from side to side. 



" Several methods of rearing them were tried. The majority 

 were placed in a large glass vessel containing mud, living grass, and 

 water. Some were put into jars containing only water, others in 

 dishes containing moist sand, others, again, in vessels containing 

 sand and water so arranged that there was a pool at one end of the 

 vessel and moist sand at the other. 



" The larvae in the vessel containing mud, grass, and water did 

 well, but many were devoured bypredaceous insects — e.gr., dragon-fly 

 larvae — introduced by accident in the mud and water, and others 

 perished owing to the grass dying and fouling the water during 

 transit. Eventually sand and water in Petri dishes was found to be 

 best, as it could be kept clean and the larvae easily located when 

 wanted. 



" At first they were fed on tiny crustaceans dredged from rain 

 pools, but during transit, when these could not be obtained, scraps 

 of freshly-killed raw meat and congealed blood from the bodies of 

 gorged mosquitoes were substituted. After arriving in Khartoum 

 their diet consisted of earth-worms, as a plentiful supply of these 

 could always be procured. 



" They grew very slowly and at greatly varying rates. Two 



