FIELD BOOK OF PONDS AND STREAMS 



have biting mouth parts and are dull-colored — dark brown, 

 yellow, or pale green. Similarly they are squarely built but 

 their tail filaments are very much shorter than those of the 

 nymph. They hold their two pairs of wings closely to the 

 body with the wide hind ones plaited and hidden beneath the 

 front ones (Fig. 148). They do not fly about very much. 



Fig. 148. — Adult stonefiy, Pteronarcys dorsata. 



Many species skulk about in any shady place which is near 

 the water but in contrast to these shade-loving species are 

 the little black Allocapnias (Capnias) and Capnellas which 

 run over the dazzling sunlit snow from January to March. 



Little is known of the egg-laying habits of stoneflies. When 

 in captivity, Perla immarginata deposits her eggs loose in the 

 water. This is probably true of many species since their 

 eggs are not found in patches on stones and sticks as are 

 those of caddis flies and some other water insects. Most 

 adults live only a short time and probably eat little or nothing. 



Habits. — With few exceptions stonefiy nymphs live in swift 

 water, swirling brooks and waterfalls (Fig. 23). They clamber 

 over the stones, keeping hold by their strong claws, always 



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