PLECOPTERA OF NORTH AMERICA 



33 



Genus PTERONARCYS Newman. 



1838. Pteronarcys Newman, Ent. Mag., 5:175. 



1907. Pteronarcys Klapalek, Bull. Internat. Ac. Sci. Boheni., pp. 1-13. 



1917. Pteronarcys Smith, Trans. Amer. Ent. Soc, 43:4:17. 



\ The largest of stoneflies, 

 with stout depressed linear 

 / bodies, long antennae, short 

 tails and broad heavily net- 

 veined wings. Color dark 

 brown, varied (sometimes 

 rather brightly in life) with 

 intersegmental markings of 

 rufous, orange and yellow. 

 Ocelli 3 in an equilateral tri- 

 angle. Frontal tubercles 

 prominent, supra-antennal 

 plate well developed. 



Prothorax broader than 

 long, bearing a pale median 

 yellow line and lateral em- 

 bossed markings upon the 

 disk. First tarsal segment 

 twice as long as the second 

 and the third a little longer 

 than the two preceding it. 

 N y m p h a 1 gills persistent 

 (13 pairs) shrivelled and in- 

 conspicuous. Wings concol- 

 orous, or somewhat clouded on the veins. 



Abdomen depressed-cylindric, paler beneath ; tails 

 brown, paler at the base. Genitalia highly specialized 

 and very peculiar, meriting special study because they 

 hold almost the only reliable criteria for distinguishing 

 the species. These being made the basis of the follow- 

 ing keys, it has been necessary to treat the two sexes 

 separately. 



These insects are crepuscular or nocturnal in habits 

 and are consequently little observed. Hardly anything 

 has been written of their habits. Newport (Trans. Linn. 

 Soc. Lond., 20:433) records that P. proteus was found in 

 great numbers at a waterfall in Magog River, hanging to 

 the rocky sides that were wet by spray, or concealed in 

 the crevices of the rocks. He also states that P. regalis (P. 

 dorsata) was taken by Doubleday on wet evenings. Hagen 



Pig. 10. Pteronarcus dorsata Say. 



