Studies of 
North American Plecoptera 
feel. bRISON 
HIS paper is a result of the contin- 
uance of studies of the stonefly 
fauna of Illinois started in 1926 
and expanded within more recent years to 
include the fauna of North America. 
Three previous papers of mine have dealt 
entirely or in part with Lllinois material 
of these aquatic insects; the first dealing 
with the fall and winter species only 
(1929), the second with all the then 
known Illinois species (1935a) and the 
third with additional information and re- 
cordings of species (1937). 
In 1937 the Illinois list of stoneflies 
stood at 38 species plus a questionable 
identification of a capniid female and the 
nymph of a species of Isoperla not place- 
able to species. Studies of Illinois material 
since 1937 have revealed the identity of 
the capniid adult and the Isoperla nymph, 
and added nine additional species to the 
‘Ubinois list. 
Besides the study of Illinois Plecoptera, 
work has been in progress on the stonefly 
fauna of North America in general as a 
tesult of the availability of a large amount 
of adult and nymphal material submitted 
for identification by others or directly 
secured on collecting trips made by various 
members of the Illinois Natural History 
Survey staff. The Great Smoky Moun- 
tains National Park region and the states 
of Wisconsin and Michigan have been par- 
ticularly singled out for collecting trips 
because of their nearness to Urbana, IIL., 
and the occurrence in them of numerous 
species not found in Illinois which are 
fairly representative of more northern and 
eastern sections of the United States and 
Canada. Numerous other collecting trips 
With Special Reference 
to the Fauna of Illinois 
producing much material, trips often 
coupled with vacations or other duties, 
have been made by various staff members 
to almost all parts of the United States, 
with the exception of the southwestern 
states, and to southern Canada. In addi- 
tion to collection of adult and nymphal 
stonefly material in quantity, considerable 
attention always has been given on these 
trips to the taking of mating pairs and the 
rearing of adults from nymphs. Some of 
the rearing of adults from nymphs has 
been done at the point of collection by the 
use of special rearing cages and by working 
at night to secure adults emerging from 
nymphs. Other nymphal material has been 
transported to Urbana from distant locali- 
ties and then reared. 
Another phase of activity in connection 
with the Survey’s study of the stonefly 
fauna of North America has been the care- 
ful examination of existing types. ‘The 
collections of the Museum of Comparative 
Zoology, Cambridge, Mass., and of Cor- 
nell University, Ithaca, N. Y., in addition 
to the Illinois Natural History Survey 
collection, are particularly rich in typic 
specimens of Plecoptera, and all of the 
North American types in these collections 
have been critically studied upon several 
occasions. “The writer has also been privi- 
leged to study most of the other types of 
North American Plecoptera scattered here 
and there in various collections throughout 
the country. 
The result of all this collecting, rearing, 
identification of material and study of 
types has naturally yielded much new in- 
formation regarding the association of 
nymphs with adults, the distribution of 
[E2358] 
