86 



Dragon-flies and Damsel-flies 



winged imagoes busily going on. The nymphs crawl out of the water, and 

 up on stones or projecting sticks, or on bridge-piles or the sides of boats, 

 or on the stems of weeds growing by the water's edge. Here they cling quietly, 



awaiting the moment when the chi- 

 tinous body-wall shall split lengthwise 

 along the back of the thorax, and the 

 made-over body inside with its damp, 

 compressed wings, its delicate trans- 

 parent skin, and changed mouth-parts 

 and legs shall slowly work its way out 

 of the old nymphal coat. The nymphs 

 of some dragon-flies and damsel-flies 

 crawl out among the weeds and grass 

 of the shore for some distance before 

 choosing a resting-place, and none of 

 these will be very readily seen. But careful searching in a place from which 

 winged individuals are occasionally arising will soon reveal the transforming 

 in all of its stages (Fig. 116). It takes some time for the emergence of the 

 damp, soft imago from the nymphal skin, and some further time for the 

 slow expanding and drying of the wings, and the hardening of the body- 

 wall so that the muscles can safely pull against it. When all this has come 

 about the imago can fly away. But even yet the colors are not fully acquired 



FlG. 116. The issuance of an adult white 

 tail, Plathemis trimaculata, (After Need- 

 ham; natural size.) 



FIG. 117. Adult and last exuvia of the whitetail, Plathemis trimaculata. 

 (Natural size.) 



and fixed, and these fresh imagoes have an unmistakably new and shiny 

 appearance. They are called teneral specimens. Usually the emergence 

 of nymphs from the pond and the subsequent transforming cease by the 

 middle of the forenoon, and after that one can find only the frail, drying 



