5IO REPORT OF THE 



level of the water for a distance of perhaps 20 yards, he was able during the month 

 of June to collect 170 cast skins from the boarded side. This number may possibly 

 represent one-half of the nymphs which found sustenance in this limited area 

 of water, figure i. Still further evidence of the abundance of these insects was 

 observed by the writer a little later in the season, when this portion of the stream 

 was cleaned out and the mud and accumulated debris on the bottom were thrown 

 upon the bank. Only a few minutes after this fluid or semi-fluid matter had been 

 cast upon the land one could see here and there a movement, and out would wriggle 

 a dragon fly nymph. These creatures were so abundant that it was very easy to 

 collect a quart or more by picking them from the material shoveled out of the creek. 

 Some quantitative studies made by Dr. Needham a little lower down on this same 

 stream showed that in a. space of only 15 square feet, extending from the bank out 

 into the stream, there were 26 nymphs of these larger dragon flies. 



These figures give some idea of the immense numbers of these forms which exist 

 under favorable conditions, and as they are very voracious, they require a large 

 amount of food. They prey not only upon themselves but upon other insects and 

 to some extent upon smaller fishes and in turn fall vicams to larger fish and other 

 inhabitants of the stream that may be powerful enough to overcome them and keen 

 enough to detect them. The studies of Prof. Forbes show that dragon fly nymphs 

 comprise 25 per cent of the food of the grass pickerel, and in the croppie, the pirate 

 perch and the common perch the proportion ranges from 10 to 13 per cent. 



The following brief notes on various dragon flies, studied at Saranac Inn, were 

 taken from Dr. Needham's report on the work done in 1900. See Bulletin 47 of the 

 New York State Museum for tables for the separation of the species and other 

 details. 



OpJiiogoviplius aspcrsus Morse. This form, hitherto known as a very rare species, 

 was common at Saranac Inn. Many images of both sexes were observed flying 

 over Little Clear Creek in places where the shallow current rippled over sand. The 

 males would fly back and forth a few times and then rest for a while on some promi- 

 nent twig near shore, generally on the higher bank. They were not difificult to 

 approach or to capture when at rest. Except when ovipositing, the female seemed 

 to remain less of the time in the vicinity of the water, and then she makes a suc- 

 cession of sweeps back and forth near the head of some little ripple, striking the 

 water, after a few short flights, again and again near the same place and leaving her 

 eggs in it. The nymphs, plate 3, figure 5, were very common in the sandy bed of 

 the creek, and their cast skins were abundant along the banks through the months 

 of June and July, sticking to some support within a foot of the edge of the water. 



