ODONATA OF THE VICINITY OF GO HOME BAY 91 



SESSIONAL PAPER No. 39b 



small pond filling a depression in the almost bare rock and from this pond three 

 species of Odonata were emerging in large numbers, viz., Enallagma hageni, Isch- 

 nura verticalis and L. quadrimaculata. Along one side of the pond was bare rock 

 and in the few clumps of small reeds that were scattered along this shore, large 

 numbers of exuvise of the last-named species were found. One or two emerging 

 imagos were also noted, while resting in the bushes of a dense thicket on the op- 

 posite side of the pond, which was only a few feet wide, were scores of teneral 

 imagos. 



The unusual abundance of this species here was probably due to the lack of 

 competition with other large species, there being apparently no others present, 

 although I found a single dead example of Leucorrhinia intacta in a cobweb, 

 which had probably developed in the same pond. 



It may be noted that the season for emergence was somewhat later here than 

 at Go Home Bay. 



Full-grown nymphs of this species were also collected by Mr. Wodehouse at 

 the French River, June 19, 1912. 



Libellula exusta julia (Uhler) Ris. 



The scarcity of other species of Libellula in this region is fully compensated 

 for by the multitudes of this form, which fly about almost every marshy bay or 

 pond during June and July. 



In t]ie decaying organic matter at the bottom of such swamp waters, where 

 other species of the genus are seldom found, L. exusta julia seems to find ideal con- 

 ditions of environment, while in the ponds of agricultural districts, such as those 

 in the environs of Toronto and Lake Simcoe, where L. pulchella, lydia, quadrima- 

 culata and luctuosa are the prevailing species, julia is rare or wholly absent. It is 

 not, however, quite uniformly distributed in the swamp waters of Go Home Bay, 

 for in a small undrained pond on ''Split Rock Island," just off the outer coast, we 

 were unable to find the species. This pond (Plate VIII, Fig. 33) is surrounded by 

 sphagnum bog and the aquatic vegetation is very scanty. 



Full-grown nymphs were common in dredgings made on May 31, 1912, and 

 during the week following. Imagos were first noticed on June 7 and had become 

 abundant by the 13th. They continued so for about a month, their numbers 

 dwindling during the last half of July until the 30th, when the last specimen was 

 noted. A few specimens emerged in the laboratory during the latter half of June. 



This dragonfly is not only common about its breeding-grounds, but also in 

 the open rocky woods, where it takes short flights, frequently settling on the bare 

 rocks after the manner of Gomphines. In fine still weather the males may be seen 

 chasing each other swiftly and erratically over the water and are somewhat con- 

 spicuous objects on account of the white pruinosity of the thoracic dorsum and 

 basal segments of the abdomen. 



L. exusta julia ranges northward at least as far as Nipigon, Lake Superior. 



