38 



Fielding (J.. W.). Notes on the Bionomics of Stegomyia fasciata, 

 Fabr. (Part I). — Ann. Trop. Med. Parasit., Liverpool, xiii, no. 3, 

 10th December 1919, pp. 259-296. 



Ill the course of breeding large numbers of Stegomyia fasciata for 

 the requirements of the Austrahan Institute of Tropical Medicine 

 observations were made on various points that required elucidation. 

 A chart is given showing the temperature and humidity readings in 

 the grounds during the period occupied by these experiments. The 

 method of keeping and feeding the adult mosquitos is discussed. 

 An exclusive diet of blood for the females and of bananas for the males 

 proved most satisfactory. The egg-laying period of a fertilised 

 captive female is from 40 to 72 days with an average of about 750 

 eggs. Apparently no preference is shown for any place for the purpose 

 of oviposition, the eggs being deposited in almost any receptacle 

 containing water. In experiments to ascertain if ovipositing females 

 prefer contaminated water it was noticed that sugar and water 

 appeared to be the most attractive bait, although this gave unfavour- 

 able results as food for the larvae ; no eggs were laid in water 

 containing more than 70 per cent, of sea-water. During the summer 

 the eggs hatched on the second or third day, and during the winter 

 on the third or fourth day. Experiments with regard to the influence 

 of drying on the hatching of eggs, cooling of resistant eggs, submergence 

 in small and large quantities of water, and retention of eggs by gravid 

 females, show results similar to those of previous authors [R.A.E., 

 B, iv, 161]. When eggs were dried over calcium chloride, after 

 7 days treatment 80 to 90 per cent, hatched, after 19 days, 8 to 15 

 per cent, and after 26 no eggs hatched. Of resistant eggs immersed 

 for 30 seconds in lysol and then re-immersed in water 87 "9 per cent, 

 hatched in about 24 hours. Soap solutions produced similar results 

 to petroleum soft-soap emulsion and 69*2 per cent, of the resistant 

 eggs hatched in 24 hours. The position of the eggs, w^iether floating 

 or submerged, has little influence upon the hatching. From 150 

 dried eggs immersed in sea-water 77*3 per cent, hatched, whilst from 

 an equal number placed in tap water 83*3 per cent, hatched. No 

 adults were reared from freshly laid eggs placed in tap water containing 

 more than 40 per cent, of sea-water. 



The development of larvae under artificial conditions at room 

 temperature is apparently not influenced by the presence or absence of 

 light, but excessive heat increases the mortality. 1 he approximate 

 maximum temperature that the larvae and pupae are capable of 

 withstanding without great mortality is about 105° F. Experiments 

 have been made with various foods, iacluding polished rice, 

 mango leaf, fowl faeces, broth and fly maggots, etc., added in varying 

 quantities to the water containing larvae ; the results are shown in tables. 



The length of life of adults varies greatly with the diet, 7 days 

 being the maximum for unfed individuals, and 93 days was the 

 longest period when a suitable diet such as blood and bananas was 

 provided. No oviposition occurred with females fed on food other 

 than blood, with the exception of the cases in which peptone and 

 sugar was substituted, when 60 per cent, of the eggs laid proved 

 fertile. Fertilisation of the female greatly increases the production 

 of eggs. 



