408 THE CANADIAN' ENTOMOLOGIST. 



particularly near the apex of the abdomen (fig. 3). The skin, 

 normally dark green in colour, is rendered almost transparent owing 

 to its great distension, and through it can be seen a white irregular 

 mass of parasitic material. Upon dissection, this parasitic mass 

 is found to consist of countless spores. Four distinct types of 

 spores were found in different localities. These represented, prob- 

 ably four, or even more, species. The simplest type was a plain 

 ovoid, about 5m by S/j. in size. Another, similar in size, had at one 

 end a flattened disc. In a third, this disc was replaced by a stout 

 flagellum-like organ about 2-3 times the length of the spore, while 

 the fourth resembled the third, but had in addition two raised 

 annulations around its equatorial region. The first type of spore 

 represented, probably, a normal species of the genus Glugea, of 

 which three more species were found during the following fall. 

 Unless the spores bearing appendages belong to the Myxosporidia, 

 S.S., which seems to be improbable, they represent entirely different 

 types to anything previously described. Up to 80% parasitism 

 was recorded, every case of wliich is believed to have been fatal. 

 This could not be proved definitely since all Simulium larva' kept 

 under observation in captivity died. The following observations 

 tend, however, to confirm this supposition. No pup^ie containing 

 parasites could be found, even where 80% of the larva^ had been 

 infested. No reproductiv^e organs were found in parasitised larvae. 

 There is very little fat body stored up in these larvae. The volumin- 

 ous proportions of the parasite would require an enormous rent in 

 the ectoderm in order that it might escape, and were it to pass over 

 into the adult it is inconcei\'able that the latter would be able to 

 escape from the water when so hampered. 



Throughout the summer isolated specimens of S. bractcalnm 

 were present in the streams. These were casually examined, but 

 no parasites were found. By the beginning of October larvae of 

 this species were abundant. S. vitlatnm was represented, also, by 

 a few specimens, and by the middle of November 5. hirtipes was 

 once more hatching out from recently deposited egg masses. The 

 latter species seems to aestivate throughout the Summer, for no 

 signs of it were seen between the end of May and the beginning of 

 October. 



The larva^ present in the streams during the fall months were 



