70 MARINE AND FISHERIES 



5 GEORGE v., A. 1915 



Aeshnidae. 



Gomphinae. 

 22. Hagenius brevistylus Selys. 



The full-grown nymphs of this large Gomphine are not infrequently met with 

 during the first half of summer among roots and debris along the edge of the 

 lake shore. They breed in the bay and river but do not occur in the smaller inland 

 lakes. They do not, however, frequent the barest or most exposed parts but show 

 a preference for the more sheltered spots, where the bottom is more or less sandy. 

 The younger nymphs are occasionally dredged from depths of six or eight feet. 

 Four sizes of nymphs were found, including the full-grown stage, and it would thus 

 appear probable that the nymphal life extends over a period of three years or 

 more. 



To ensure success in rearing the nymphs of this species, the water in the breed- 

 ing-jar should be kept as fresh as possible. In our first efforts, this point was not 

 strictly observed and the two full-grown nymphs which we were attempting to 

 rear died shortly before the usual time for emergence. They had crawled out of 

 the water and remained out for about four days, when we replaced them in fresh 

 water, but they soon died. They had evidently not emerged for the purpose of 

 transformation as we had at first supposed. 



The large formidable-looking imagos are first seen early in July, becoming 

 common a few days after their first appearance. In 1907 they began to emerge 

 on the Station Island on July 2nd, but in 1912 they were not observed until July 

 9th. They were still not infrequent on Aug. 10th of the latter year, but by the 

 20th they had nearly disappeared. 



During the period of emergence and for a short time afterwards, this huge, 

 conspicuously-coloured dragon-fly may be seen about the Station Island, flying 

 rather slowly and within a few feet of the ground. It is fond of basking in the 

 sun in sheltered openings in the thickets along the shore, and when disturbed 

 it does not usually fly very far. It is also frequently seen flying swiftly over the 

 water, close to the shore. 



The food of the adult Hagenius consists chiefly, if not wholly, of other dragon- 

 flies. We have not observed it feeding on any other kind of insect. We have 

 taken it while devouring Gomphus lividus, G. exilis, Neurocordulia yamaskanensis 

 and Tetragoneuria cynosura simulans. 



23. Gomphus brevis Hagen. 



This is the rarest of the four species of Gomphus found in the vicinity of Go 

 Home Bay. The adults are most frequently seen in the neighbourhood of rapids, 

 but also occur in the more exposed shores of the bay, and one was observed on 

 South Pine Island, which lies in the open water of Georgian Bay, about 3 miles 

 out from the coast. Another was taken on the Giant's Tomb Island. The nymphs 



