222 ^HE CANADIAN ENTOMOLOGIST 



About two miles west of the station, on the north side of the river, I 

 found, at the foot of a mountain, a small mossy bog, fed by springs and by 

 the seepage from a small cold mountain brook. The bog was partly enclosed 

 by spruce forest and supported a scattered growth of stunted white spruce and 

 willows, shrubby cinquefoil, and a few other swamp jjlants. but, excepting the 

 moss, which was partly submerged, there was practically no aquatic vegetation, 

 neither standing nor floating. Here were two species of dragonflies flying and 

 ovipositing. One was Somatochlora frankUui Selys, the other Acshna sitchcnsis. 

 The latter was the commoner of the two, but was far from numerous, the bog- 

 often appearing for many minutes at a time to be devoid of dragonfly life. 



The males of A. sitchcnsis flew low, as a rule, only a foot or two from 

 the ground, sometimes apparently at random over the. bog, sometimes following 

 the stream for some distance, but not covering a definite beat. They flew less 

 swiftly than most Aeshnas and frequently dropped to the surface of the water 

 for an instant, in a manner somewhat suggestive of an ovipositing female. 



The females were frequently observed ovipositing in the wet moss about 

 the edges of the small puddles in the bog, many of which were less than a 

 square foot in area. The manner of oviposition was quite like that of other 

 Aeshnas. The insect would light on the moss and thrust the abdomen into it 

 in various directions, following no regular plan. Usually she remained at one 

 spot less than half a minute, then flew on a few yards and repeated the operation. 

 Once or twice copulating pairs were seen to rise from the bog and fly to the 

 neighbouring trees. 



A prolonged search was made for nymphs and exuviae, but although 

 Somatochlora exuviae and a few young nymphs were found, no trace of the 

 early stages of sitchcnsis appeared. 



I was now, however, on the right track. I had at last penetrated the 

 mystery of this strange dragonfly's haunts, which proved to be the same as 

 those of the equally little-known Somatochlora franklini. It may be recalled, 

 however, that the correct solution of this puzzle was already hinted at by Mr. 

 F. C. Whitehouse (Can. Ent., XUX, 1917, p. 100), who says: "I incline 

 strongly to the opinion that the true breeding of this northern insect is muskeg, 

 which may account for the nymph being still unknown." 



On August 5 I left Field and arrived at Banff on the same day. I told 

 my friend, Mr. N. B. Sanson, Curator of the Rocky Mountain Park Museum, 

 of my experience at Field, whereupon he kindly offered to conduct me to a 

 bog which he thought might prove interesting in a similar way. This bog, 

 which we visited on August 9, is at the foot of Mount Rundle, and proved to 

 be very like the one at Field, but much larger and in every way more pro- 

 ductive. It appeared to be fed by seepage from a cold mountain stream. At 

 the lower end of the bog there were two or three small ponds around which 

 cat-tails and other standing aquatic plants grew, but the water was very cold 

 and no dragonflies were seen in this part. The upper and middle parts of the 

 bog were mossy and practically without standing aquatic plants and the open 

 areas of water were mere puddles like those at Field. The water here was 

 also warmer. One could walk through it without sinking more than a foot or 

 so, if careful to pick out the firmer-looking moss hummocks. 



