NEUKOPTERA, EPHEMERIDA, AND ODONATA 119 



beef, mosquito larvse, or bits of earth worm they will be 

 seen to molt. In some cases the nymph (pupa) will climb 

 a stick or stem of a water plant during a night in June, and 

 early the following morning from a sli t in the skin of its 

 back the adult insect will come forth. In midsummer 



FIG. 140. Dragon fly and larva (Plathemis lydia). Photograph natural size. 



the eggs are laid on the surface of the water or on some 

 object beneath the surface. 



Most dragon flies alight with expanded wings, but a 

 group of the more slender-bodied ones resting with wings 

 folded goes under the name of damsel flies. So far as known 

 all dragon flies, otherwise called devil's darning needles, 

 snake feeders, and snake doctors, are harmless and bene- 

 ficial insects. The larvae feed on mosquito larvae and other 

 aquatic forms, while the mature insect consumes large 

 numbers of mosquitoes. To note one's appetite hold it by 



