IO2 



ELEMENTARY E\T()M( )L( )GY 



and molts for the last time, the adult quickly flying away and 

 leaving the cast skin, which is often found intact and gives an 

 excellent idea of the structure of the nymph, so remarkably unlike 

 the adult in both form and habit. 



FIG. 132. Dragon-fly (Libellula pnlchella}. (Slightly reduced) 

 A, last nymphal skin ; B, adult. (After Folsom) 



SUMMARY OF THE NERVE-WINGED INSECTS AND THEIR 



RELATIVES 



A . With complete metamorphosis : 



Order Neuroptera. Wings equal ; numerous cross veins. 

 The dobsons (Sialidae). Larvae aquatic. 

 The aphis-lions (Chrysopidae). Feed on aphides, etc. 

 The ant-lions (Myrmeleonidae). Larvae make pits in soil. 



Order Mecoptera. Scorpion-flies. Elongate head, and tip of abdomen fang- 

 like. Larvae live underground. 



Order Trichoptera. Caddis-flies. Wings with few cross veins and clothed 

 with hairs. Larvae live in water, many being case bearers. 



B. With incomplete metamorphosis (Pseudoneuropterd) : 



Order Ephemerida. May-flies. Fore-wings much larger ; mouth-parts rudi- 

 mentary. Nymphs aquatic. 



Order Plecoptera. Stone-flies. Hind-wings larger and plaited beneath the 

 fore-wings when at rest. Nymphs aquatic. 



Order Odonata. Dragon-flies and damsel-flies. Wings about equal in size, 

 with a nodus on the front margin. Nymphs aquatic. 



