163 



'The maximum period during which the spermatozoa remained active 

 in the spermothecae of the female was 62 days ; the female in cjuestion 

 laid further batches of eggs after this period, but none were fertile. 

 One male fertilised 10 out of 21 females, but these as a whole produced 

 few eggs. This may have been due to the fact that insufficient food 

 had been supplied in the larval stage. Dry chmatic conditions proved 

 most fatal to the adults. Natural enemies included the ants, Mono- 

 moriiim pharaonis, L., and Solenopsis geminata, F., the spider, XJlohorus 

 Jeniculatus, the scorpion, Isometrus maculatus, small Mantids, two 

 species of wall-haunting lizards and a gecko. 



Larvae and pupae of S. fasciata reared in captivity were heavily 

 parasitised by the gregarine, Lancasteria culicis, Wenvon. Bacteria 

 occurred in the larval gut and adult stomach, and in the latter yeasts 

 were also present. 



Observation^ were made on the bionomics of certain forms alUed to 

 B. fasciata. Larvae of S. sugens were obtained from small rock pools. 

 Eggs laid by adults arising from these larvae incubated in captivity 

 in two days. The eggs and larvae of this generation were affected by 

 heat, cold, and drought in a similar manner to those of S. fasciata. 

 Storage of the eggs under moist conditions was apparently less favour- 

 able than in the case of S. fasciata. Larvae became full-grown in three 

 days, pupated wdthin four or five days, and adults emerged on the 

 sixth day. Under natural conditions the developmental period was 

 probably shorter. No wild adults were captured ; those obtained 

 in the breeding cages paired at night or in a darkened cage, and among 

 the females, feeding was in no way connected with pairing. The 

 number of eggs laid was limited to two batches, but in nature probably 

 more are deposited. The duration of Hf e of the adult female extended 

 in some instances over a month. Eggs of S. simpsoni were resistant 

 to drought, as in the preceding species. Captive females fed readily at 

 night on human blood ; pairing was not observed and only infertile 

 eggs were laid. The duration of the female Hfe exceeded a month. 

 Observations on S. luteocephala were very similar to those recorded 

 for S. simpsoni. Larvae and adults of OcJilerotatus apicoannulatus, 

 O. minutus and Uranotaenia ornatus were obtained. Eretmopodites 

 quinquevittatus and E. chrysogaster were collected from water in tins, 

 etc, and E. dracaenae from leaf whorls and leaf axils. Pairinff and 

 feeding on human blood took place and eggs were deposited by 

 E. quinquevittatus. They were laid beneath the surface of the water 

 and were probably not resistant to drought, since all hatched within 

 a few days and those removed from the water collapsed on dryino-. 

 The eggs were of two kinds, large and small ; the former hatched in 

 two or three days, the latter in five or six days. Adults fed readily 

 on human blood, but man is probably not the normal host. Those 

 supphed with honey, water and banana Uved for two or three weeks. 



The breeding and dispersal of mosquitos in Freetown is dependent 

 on chmatic conditions, and especially on the character of the onset of 

 the rainy season and the tornado at the beginning of March. Mosquitos 

 are usually carried down the estuary of the Sierra Leone River to the 

 town and beyond it to the shipping in the harbour. It is therefore 

 important that drainage measures should be extended to the outlying 

 districts of the town and that operations against breeding places should 

 be begun at the commencement of the rains. 



