404 Phylum Arthropoda 



about 200 first stage larvae. The main objection to the rearing apparatus 

 was that it did not solve the difficulty of making a series of continuous 

 observations of individual larvae at regular intervals. This fact was due 

 to the frequent changes of location of the larvae over the inner surface 

 of the large-bore tube in their constant search for optimum conditions 

 for feeding. The intervention of 3 glass surfaces in contact with water 

 between the larvae and the observer also increased the difficulties of 

 making accurate observations. 



Eggs collected immediately after oviposition took 5 to 6 days to 

 develop in the laboratory, at a temperature of about 16 C. in water 

 aerated and circulated by means of a jet of compressed air. Eggs kept 

 on moist blotting paper and in a very humid atmosphere took a similar 

 time to develop. It may be noted that non-viable eggs, after the 2nd 

 or 3rd day, may easily be distinguished by their opacity from their 

 normal neighbors. 



When mature, the larva of S. ornatum forms its cocoon and pupates 

 on whatever substratum it may happen to occupy at the time. The 

 duration of pupal life varies according to temperature. At a constant 

 temperature of 21 C. it was as short as 3.75 days, while at lower 

 temperature it might extend to 12 days. 



While no difficulty was experienced in obtaining large numbers of 

 adults from pupae in the laboratory, the occasions on which they were 

 taken on the wing in nature were few. Attempts to induce the flies to 

 feed in the laboratory on human and rabbit hosts failed both with those 

 caught in the open and those reared in the laboratory. Cattle and sheep 

 in the vicinity of the stream did not appear to be molested by any species 

 of simuliid flies. In the laboratory flies were offered moistened sugar and 

 raisins, but they were not observed to feed on these. 



M. E. D. 



Bibliography 



Cameron, A. E. 1922. The morphology and biology of a Canadian cattle-infesting 

 black fly, Simulhim simile, Mall. Canad. Dept. Agric. Bull., n.s. No. 5. 



Edwards, F. W. 1920. On the British species of Simulium. II. The early stages. 

 Bull Ent. Res. 11:211. 



Puri, I. M. 1925. On the life-history and structure of the early stages of the 

 Simuliidae (Diptera, Nematocera). Paras. 17:295. 



