138 



No. 1 had grown and greatly increased in size four days later, while 

 those in No. 2 had hardly grown and were also more sluggish in their 

 movements. The waters of both containers, together with the 

 respective larvae, were therefore then mixed and more straws from 

 horse manure added. To determine the optimum temperature with 

 the above food supply for rearing the larvae in the laboratory, eight 

 lots of twenty larvae, of as nearly as possible one size, were placed in 

 eight small beakers, together with equal supplies of water from the 

 main container. These beakers were placed on a sheet of copper, 

 heated by a small Bunsen flame at one end, at varying distances from 

 the heated end. On the temperature of the water becoming constant, 

 it was found to vary between 16° C. and 41° C. according to the position 

 of the beakers. In beaker No. 4 (25 '9° C), the larvae seemed to do 

 best and the mosquitos bred from this beaker were certainly the 

 largest and strongest specimens. In beaker No. 3 (23'8° C), the 

 imagines, when they emerged, were perhaps equally fine specimens, 

 but took, on an average, three days longer to complete their meta- 

 morphosis. At temperatures below this the metamorphosis was 

 considerably prolonged, while at higher temperatures the average 

 date of emergence was considerably advanced. With the food supply 

 and light conditions used, the optimum temperature was from 23° to 

 26° C, the average larval period being 10 days, and the average pupal 

 period, 6. On emergence, the mosquitos were placed in cages made 

 of a wooden box with top and bottom removed and screened with 

 butter muslin. Mating took place almost as soon as the insects were 

 able to fly. A guineapig furnished the food-supply for the adult 

 females, a black one being chosen on account of the mosquitos' 

 preference for that colour. On one occasion a white guineapig was 

 substituted, but the mosquitos could not be induced to attack it at 

 all readily. Before their first meal, the mosquitos did not attack in 

 the voracious manner they adopted at subsequent meals. Under 

 laboratory conditions the males live from ten days to three weeks, 

 while the females live from a month to six weeks, some even being 

 alive after two and a half months. A sixth generation has now been 

 produced without loss of size or vitality. 



The author also records the finding of Culex pipiens in enormous 

 numbers in a sump 120 feet below ground at the Highgate Station of 

 the Underground Railway. A list of eleven works dealing with 

 mosquito life-histories is given. 



Stevenson (A. C.) & Wenyon (C. M.). Note on the Occurrence of 

 Lankesferia culicis in West Africa. — Jl. Trop. Med. & Hygiene, 

 London, xviii, no. 17, 1st September 1915, p. 196. 



The occurrence of Lankesteria culicis, Ross, in Stegomyia fasciata 

 obtained from Sierra Leone is of great interest. L. culicis has now 

 been recorded from India, South America, Baghdad and West Africa. 

 The Gregarine sporocysts must have been submitted to the same 

 amount of dessication as the mosquito eggs, and the larvae, hatching 

 from the eggs, became infested by ingesting these sporocysts. The 

 gregarine infection has passed through several generations of mosquitos 

 bred in this country. 



