140 



Illinois Natural History Survey Bulletin 



Vol. 27, Art. 2 



in and love of stoneflies which continued 

 through the rest of his life. Prison fol- 

 lowed the development of these little 

 stoneflies. which proved to be the small 

 group called winter stoneflies. He discov- 

 ered that little was known concerning 

 the fauna of the Midwest and began a 

 study of the group for Illinois. The first 

 report on stoneflies treated a few small 

 families comprising the winter stoneflies 

 (Prison 1929). 



The collecting and rearing of species 

 of the other families in the order were 

 begun. Rearing these insects proved to 

 be diflflcult because the laboratory water 

 available at Urbana did not sustain the 

 stoneflies. Copper cages on a raft placed 

 in a stream were eventually devised to 

 overcome this difficulty, but the losses of 

 these expensive cages by vandalism finally 

 proved so great that the practice was dis- 

 continued. A considerable number of 

 species were reared from emerging 

 nymphs caught at the water's edge. By 

 one means or another, all the Illinois spe- 

 cies were finally reared. Six years after 

 publication of the winter stonefly report, 

 a report covering all the Illinois Plecop- 

 tera appeared (Prison 1935). 



Prison found sets of nymphal charac- 

 ters which appeared to have great prom- 

 ise for indicating natural groupings of 

 the species and genera, indications such 

 as Malloch had previously found when 

 exploring characters of the larvae and 

 pupae of Diptera. The studies of stone- 

 fly nymphs set the stage for what might 

 be called the modern classification of the 

 order and stimulated emphasis on the 

 study of immature stages in subsequent 

 Survey projects on several other orders 

 of insects. 



These insects proved so fascinating that 

 Prison's studies did not long stop at the 

 boundaries of Illinois. Through material 

 obtained on vacation trips and at other 

 opportunities, the stonefly collection was 

 enlarged to cover all of North America. 

 With large series available from diverse 

 areas of the continent, it became apparent 

 that many of the old species were in real- 

 ity species complexes, and as a result 

 many of the Illinois populations had to 

 be described as new. The results of these 

 latter developments in the stoneflies were 

 published in the Bulletin (Prison 1937, 



1942rt) and as shorter papers in various 

 entomological journals. 



Megaloptera. — These, the alderflies 

 and dobsonflies, were collected during the 

 aquatic work on stoneflies and caddis- 

 flies; some specimens were received from 

 fishermen who had encountered them 

 along streams and had sent them in for 

 identification. Attempts to identify these 

 Megaloptera by means of then current 

 literature proved unsatisfactory. In the 

 alderfly genus Sialis, characters noticed 

 in the male genitalia seemed to provide 

 an excellent means for positive determina- 

 tion of the species and an analysis of these 

 characters led to a re-evaluation of the 

 species in the genus, many of which 

 proved to be new. About half a dozen 

 species were found in the material from 

 Illinois and surrounding states. As part 

 of an effort to learn something of the en- 

 tire distribution pattern of the Illinois 

 species, the study was extended to cover 

 the fauna of the whole continent. The 

 report on this study was published in the 

 Natural Historv Survev Bulletin (Ross 

 1937). 



Miridae. — As the aphid project was 

 coming to a close, H. H. Knight of Iowa 

 State College agreed to work summers 

 with the Illinois Natural History Survey 

 and prepare a report on the Miridae or 

 plant bugs of Illinois. Knight was on the 

 Survey payroll for three summers. Pre- 

 viously Hart had assembled and identified 

 an excellent collection of this group for 

 the state, but since Hart's time Knight 

 had shown that characters of the genitalia 

 indicated a much larger fauna than ear- 

 lier workers had suspected on the basis of 

 the external characters they used. 



The mirid field trip pattern followed 

 that of the aphids, with the trips around 

 the state scattered through the different 

 seasons. Again host collecting was em- 

 phasized, and field headquarters were set 

 up locally in hotels. The general plan 

 was to collect until about 3 o'clock in the 

 afternoon, and then pin up the day's 

 catch. With the Miridae, this was 

 thought desirable because of the fragile 

 nature of certain diagnostic characters, 

 especially pubescence, which might be 

 brushed off if the specimens were relaxed 

 and pinned later. Many thousands of 

 specimens were collected each year, and 



