CHAPTER XI 

 ORDER PLECOPTERA* 



The Stoneflies 



The members of this order have four membranous wings, with compara- 

 tively few or with many cross-veins; in most of the forms the hind wings are 

 much larger than the fore ivings, and are folded in plaits and lie upon the 

 abdomen when at rest. The mouth-parts are of the biting type of structure, 

 but are frequently undeveloped in the adults. The metamorphosis is in- 

 complete. 



The stoneflies are common insects in the vicinity of rapid streams 

 and on wave-washed rocky shores of lakes; but they attract little atten- 

 tion on account of their inconspicuous colors and secretive habits. They 

 get their name, stoneflies, from the fact that the nymphs are abundant 

 under stones in the beds of streams. 



The body of an adult stonefly is flattened and the end of the abdomen 

 in most species, bears two, many-segmented bristles. The antennas are 

 also long, tapering and many-segmented. The mouth-parts are usually 

 greatly reduced. Indeed, in some, 

 the mandibles are almost membra- 

 nous and of little use as chewing 

 organs. In other forms they are 

 firm and well fitted for biting. This 

 is especially true of certain species 

 of the genus, Tceniopteryx. One 

 species of this genus, T. pacifica, 

 known as the "salmon fly" has be- 

 come a pest in the Wenatchee 

 Valley in Washington because it 

 eats into the swelling buds of 

 apricots, peaches, and plums and 

 often destroys them. 



Adult stoneflies are not partic- 

 ularly attractive insects for most of Fig. 130. — a stonefly. 

 them are of sober hues, black, brown, or grav, although a few which 

 frequent the foliage of plants are green (Fig. 130). As a rule, they are not 

 strong fliers and are usually found crawling about on stones or on plants 

 near streams. Interestingly enough, several of the smaller forms appear 

 early during warm days in February and March while the snow is still on 

 the ground. Several small species formerly of the genus, Capnia, but now 

 renamed Allocapma, are early spring appearing individuals. A very 

 common one, A. pygmcea, which is dark brown to black and only about 

 4 of an inch long, is known as the snow-fly because it appears on the 

 * PlecSptera: plecos (ttUkos), plaited; pteron {-wrtpov), a wing. 



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