882 FRESH-WATER BIOLOGY 



STONEFLIES (Order Plecoptera) 



The stoneflies constitute a small and primitive group of insects 

 of inconspicuous coloration and rather secretive habits. They are 

 found almost exclusively about rapidly flowing water. Every 

 spring brook will furnish a few of the smaller grayish or brownish 

 species, and every larger rocky stream is the home of some of the 

 larger forms. During the winter months the small black Capnias 

 appear, often in great abundance on the surface of the snow, 

 Capnia necydaloides appearing usually in December, and Capnia 

 pygmaea, in March. Several species of Taeniopteryx appear also in 

 March, and may often be seen on mild, sunshiny days by the 

 borders of creeks, slowly and laboriously flying along the banks on 

 warm afternoons. Species of Nemoura appear in April, emerging 

 from the waters of cold brooks, and making short flights from one 

 gray tree trunk to another. All through the summer the larger 

 species are emerging from rocky streams, but these are very se- 

 cretive in habits. They may be beaten from the bushes along the 

 stream side, but are oftenest seen in numbers about street lamps 

 and are easiest collected when attracted to lights. The green 

 stoneflies (Chloroperla, etc.) fly mainly in midsummer, and frequent 

 the fresh foliage, in the midst of which they are quite incon- 

 spicuous. 



Rudimentary wings occur in a number of the genera, Capnia, 

 Taeniopteryx, Pteronarcella, Perla, etc., and, of course, the wingless 

 species are to be found near the waters from which they emerge 

 on transformation in fact, not farther therefrom than they are 

 able to run or climb. The males alone are wingless in most cases. 

 The eggs of the females are practically mature at transformation. 

 While there is dearth of observations as to the feeding habits 

 of the adults, it is certain that they will lap up water and other 

 fluid substances, and the small grayish species eat dead grass leaves 

 and other solid food. The mandibles of the larger forms are weak 

 and rudimentary. The adult life, therefore, is probably very brief. 

 Concerning the egg-laying habits also, there is dearth of actual 

 observation. Females of many species may be taken when carry- 

 ing egg masses extruded at the tip of the abdomen ; but just 



