2A? NEW YORK STATE MUSEUM 
4 Aeschna constricta 
The nymphs of this dragon fly live in the midst of the shore 
vegetation in shallow water. The trout that eat them probably 
have to go beyond the confines of their usual feeding grounds 
to get them. The advanced stage of digestion in which the spec- 
imens were found seemed to indicate that the specimens had 
been taken during the preceding night. Aeschna nymphs 
attached to a hook were taken by the trout, but not more read- 
ily than minnows, small frogs or other bait. 
These were the largest animals the trout had eaten. The yol- 
ume of one of them would equal perhaps that of 15 to 20 Chi- 
ronomous larvae, or 30 to 40 Corethra larvae, or 5 to 7 caddis fly 
larvae, or 4 to 5 Callibaetis nymphs. They are among the most 
powerful members of the aquatic insect community and clamber 
about frequently on exposed places on plant stems, where the 
trout, if at hand, might easily seize them. 
In a small way the dragon fly nymphs are competitors of the 
trout for food. They eat small insects promiscuously, and 
doubtless many pupae of Chironomus and Corethra fall victims 
to them. They will eat young trout, also, as long as themselves. 
I demonstrated this at Saranac Inn by confining them together 
in a breeding cage. One little trout would be captured quickly, 
and then the others would be wary of the nymphs and keep 
away from them well, so that we would think they would evade 
a similar fate, but one by one they would disappear till all had 
been eaten. The Aesehna nymph approaches its prey with the 
slowness and poise and stealth of a cat till within striking dis- 
tance. Plate 5, figure B, shows a nymph of this species pois- 
ing for a stroke at a backswimmer (Notonecta). 
The adult dragon fly is shown also on this plate. Transforma- 
tion occurs in the latter part of June and in July. The female 
inserts her eggs by means of an ovipositor into the stems of 
plants just below the surface of the water. The eggs hatch in 
about three weeks, and the little nymphs at once take up their 
abode among the submerged plants and eat promiscuously any 
other animals they can overpower; they also eat one another. 
