THE CANADIAN ENTOMOLOGIST 173 



were observed during \'ery warm, still weather. The past two 

 seasons (1915 and 1916) presented a remarkable contrast in weather 

 conditions, and an equally marked contrast in the numbers of 

 dragonflies in flight at the "Pornt." The season of 1915 was almost 

 continuously cold and wet and dragonflies were so scarce that it 

 was hardly worth while collecting them. The summer of 1916, 

 on the other hand, was unusually hot and dry, particularly during 

 the months of July and August, when ^^^shna is chiefly on the wing. 

 This season was remarkable for the abundance of several species of 

 dragonflies, notably y^shna canadensis, A. constricta, Leucorrhinia 

 hitacta, Libellula pulchella and Sympetrum ohtrusiim. 



Almost immediately after my arrival at the Point, on July 

 12, 1916, I noticed that A. canadensis was very plentiful among the 

 scattered trees along the edge of a dense wood and in a somewhat 

 open grove of pine and oak. The hot, dry weather, which was to 

 last nearly all summer had already commenced. On the 19th 

 the dragonflies were so numerous in some places that one could 

 scarcely take a step without flushing one or more from the trunks 

 and branches of the trees. I often saw two or three on a single 

 trunk, and once noted five on one dead branch. 



Being curious to know whether the exuviae of this species 

 would be correspondingly abundant, I visited the nearest marsh 

 at the outlet of Wilson's Creek, a sluggish stream about three- 

 quarters of a mile to the northwest, and another at the outlet of 

 Whitefish Creek about a mile and a half to the south. A pro- 

 longed search at both places yielded only five exuviae and one full- 

 grown nymph. Not a single adult was seen at either creek. I 

 had always supposed that these two creeks were the principal 

 breeding places of these species, as there are no others within several 

 miles, but my doubts were now aroused. The absence of adults 

 was expected 'as they always leave their breeding places soon after 

 emergence, but the scarcity of nymphs and exuviae was significant. 



On July 24 I left Lake Simcoe, returning on August 5. A. 

 canadensis was now quite scarce in the woods, but A. constricta 

 was beginning to appear and became daily more plentiful. By 

 about the 15th its numbers had so increased that it was even more 

 abundant than A. canadensis had been. Copulating pairs were 

 frequently seen throughout August and in early September, steer- 



