24:6 SIR RUBERT BOYCE THE PREVALENCE, DISTRIBUTION AND 



Food of the Larvae. 



So far as one can gather there is no evidence as to the exact nature of the 

 food of the larvse. In captivity they feed largely upon amorphous matter 

 and upon the macerated remains of minute crustaceans {Cyclops sp., Dia- 

 ptomus sp., etc.), minute fragments of aquatic plants, an occasional diatom 

 and unicellular plants. 



The larvae of Stegomyia fasciata have been found in association with those 

 of several other species of mosquitos, notably with those of Cvlex fatigans 

 and to a less extent with Limatus durhami, etc. Dupree has made some 

 interesting discoveries regarding the habits of the larvse, which are commu- 

 nicated by Mitchell in her excellent memoir (/. c. p. 147). It is stated that 

 the young larvse are remarkably tenacious of life under water ; they tolerated 

 as much as three hours submergence and in some cases were resuscitated 

 after five hours ; on the other hand, adult larvae tolerated total immersion 

 for IJ to 2 hours. This habit enables them to feed at the bottom of cisterns 

 of normal depth and to remain submerged for unusually long periods. 



Resistance to Frost. 



There is apparently no direct evidence to prove that the larvae of Stegomyia 

 fasciata can survive at a temperature of freezing point, though they have 

 been found by Francis (I. c.) at Mobile, Ala., U.S.A., living in tubs placed 

 in sheltered positions during frosty weather and when the water in vessels 

 exposed to the open air was coated with ice half an inch thick. But it is 

 noteworthy that some large healthy larvae, which were found in the living- 

 room of a hospital^ died when placed in an ice-box where the temperature 

 was about 50°. It is quite evident, however, that this insect can survive 

 at a relatively low temperature, as may be gathered from the statements given 

 by Mitchell *, who says that larvae were found by her in November at Baton 

 Rouge at a temperature as low as 34° F., and further that pupation took 

 place in water at 53° F. Cold ^' stiffens ^^ the adults, but one was observed 

 by her to revive afterwards. 



YIII. Viability of the Ova after long Exposure to Dry 

 Atmospheric Conditions. 



Mr. F. V. Theobald f was apparently the first to discover that the eggs 

 of this mosquito will remain fertile for a long period, although exposed to 

 normally dry atmospheric conditions. In this instance the eggs were 

 forwarded to England from Cuba in a perfectly dry test tube. After a 

 period of two months they were placed in '^ tepid water " and the majoritj^ 

 of them produced larvae. Many of these larvae survived until the tenth day, 



* ' Mosquito Life,' p. 148, 1907. 

 t Men. Ciilicidae, vol. iii. p. 143, 



