9 8 



ELEMENTARY ENTOMOLOGY 



half to one and one half inches long ; with their long legs, and anten- 

 nae and cerci projecting from either end, they have a very distinctive 

 appearance, as shown in Fig. 125. Behind each leg is a clump of 

 hairlike tracheal gills, very similar to those found on the dobson, 

 through which they breathe. They are a favorite food of fishes, 

 particularly of brook trout, and make excellent bait. When full 

 grown the nymphs crawl upon rocks or reeds and transform to the 



adult stone-flies, the old skins 

 being frequently found in such 

 places. The adults are dull 

 grayish or brownish, the more 

 common forms being from one 

 to one and one half inches long, 

 and are usually found on foliage 

 in shady places along streams. 

 They probably take no food and 

 live only long enough to lay the 

 eggs. Some of the smaller spe- 

 cies, about one fourth of an inch 

 long, of a blackish color, are 

 often common on snow in early 

 spring, and frequent windows 

 at that time. 



The dragon-flies and damsel- 

 flies (order Odonata) are readily 

 recognized by their long, nar- 

 row, powerful wings, which are 

 about equal in size and on the 

 front margin of which is a little 

 notch and strong cross vein, called the nodus. The mouth-parts are 

 well developed and are of the biting type, both larvae and adults being 

 predacious upon other insects. The dragon-flies and damsel-flies 

 are distinguishable both as adults and as nymphs. The adult damsel- 

 fly holds the wings vertically over the back when at rest, like a butter- 

 fly ; the fore and hind wings are similar in shape, and the nymphs 

 have three long, leaf like tracheal gills projecting from the tip of the 

 abdomen. The dragon-flies hold their wings horizontally when at 

 rest, the hind wings are usually much broader at the base, and the 



FIG. 126. A damsel-fly (Lestes uncata 

 Kirby), female 



(After Needham) 



