PLECOPTERA OF NORTH AMERICA 9 



to complete the life cycle, and in some of the larger 

 species two or even three years may be consumed. 



The complete life history of a small species, Nemoura 

 vallicularia Wu, has recently been published.* This species 

 passes through 22 developmental instars and completes a 

 generation in one year. It is entirely herbivorous, feed- 

 ing upon dead vegetable matter. Heretofore stoneflies 

 have usually been considered as carnivorous, but the ex- 

 amination of stomach contents of a number of nymphs in- 

 dicate that Pteronarcys, Nemoura and others feed upon 

 vegetable matter only, while Perla, Acroneuria, etc., prey 

 upon animal forms as well as feeding upon vegetable ma- 

 terial. 



Most stoneflies do not feed in the adult stage, but some 

 species have well developed mouthparts and one species 

 Taeniopteryx pacifica Banks — (Taenionema analis Banks) has 

 been recorded as injuring the buds of fruit trees on the 

 Pacific Coast. 



COLLECTING AND PRESERVING. 



Specimens for study are best preserved in alcohol (70 

 to 80 per cent strength) . They may be pinned and spread 

 and dried and kept in boxes, as are most other insects, 

 and the general collector of insects will probably prefer 

 to keep them so; but their colors fade quickly and they 

 shrivel like primes in drying, and they form a very un- 

 attractive part of a pinned collection of insects. Our 

 method is to preserve fresh material at once in alcohol in 

 homeopathic vials, hanging the vial's to a handy wire rack 

 by a small hanger attached to the neck of each vial : the 

 vials thus hang vertically, and good corks, having no al- 

 cohol in contact with them, last a long time. We mount 

 detached wings for study outspread upon a glass slide 

 under a cover glass that is held by a strip of gummed 

 paper over each end, binding slide and cover glass to- 

 gether. All the wing figures of this volume were made 

 from such mounts. We mount the wings dry, not in bal- # 

 sam, which having the same refraction as the weaker 

 veins, render some of them invisible. 



For the study of the genitalia we snip off the abdomen, 

 boil it for a few minutes in caustic potash until the flesh 

 has been removed and only chitin remains and then keep 

 this boiled portion in the vial with the unboiled part of 

 the specimen. We do not mount it in balsam because it 



*Wu, C. F. Morphology, Anatomy and Ethology of Nemoura — Bulletin 23, 

 Entomological Series No. 3, Bulletin of the Lloyd Library, 1923. 



