142 



Illinois Natural History Survey Bulletin 



Vol. 27, Art. 2 



By 1945 it was apparent that a re- 

 port embracing all the leafhoppers un- 

 der one cover vv^as impractical, and De- 

 Long prepared the manuscript for about 

 half of the fauna, which included all 

 the subfamilies except the Cicadellinae. 

 This report was published in the Bulletin 

 (DeLong 1948). 



At this time, R. H. Beamer of the 

 University of Kansas had drawn atten- 

 tion to the tremendous number of Mid- 

 western species contained in the genus 

 Erythrojieura, the largest genus of the 

 untreated subfamily Cicadellinae. Mrs. 

 D. J. Knull had identified a large part 

 of the Natural History Survey material 

 in this genus. Most of the several hun- 

 dred species were known only from hi- 

 bernation collections, and it was felt 

 that, before proceeding with the manu- 

 script on this subfamily, the host rela- 

 tionships and other ecological informa- 

 tion should be ascertained for these 

 species. As a result the project was re- 

 aligned and a new host-collecting pro- 

 gram for the entire subfamily was dele- 

 gated to the faunistic staff of the Survey. 

 The large number of host associations al- 

 ready established have proved of interest 

 in contributing ideas concerning evolu- 

 tionary problems in insects having moder- 

 ately rigid host associations. 



Trichoptera. — A study of the caddis- 

 fllies was prompted by the importance of 

 this group in the economy of Illinois fresh- 

 water habitats. The project was planned 

 originally as a joint one with Dean Cor- 

 nelius Betten of Cornell University, who 

 had in manuscript at the time the first 

 comprehensive and useful New World 

 faunistic study of the group; his study 

 dealt with the fauna of New York. Bet- 

 ten in America and A. B. Martinov in 

 Russia had pioneered in the technique of 

 clearing the male genitalia of Trichoptera 

 in KOH in order to get a more exact 

 knowledge of these diagnostic structures. 

 Betten spent 6 weeks on the Illinois Nat- 

 ural History Survey staff in the summer 

 of 1931, his time being spent partly on 

 collecting trips around the state and 

 partly in identifying the caddisfly ma- 

 terial in the Survey collection. In 1932 

 press of other duties caused Dean Betten 

 to retire from the project, which was then 

 assigned to Ross. 



Much of the caddisfly collecting was 

 done as an adjunct to stonefly, mayfly, 

 mirid, and leafhopper collecting, but spe- 

 cial trips were made to springs and cer- 

 tain rivers, such as the Kankakee, which 

 supported unusual species. As the taxo- 

 nomic analysis of the material progressed, 

 it became evident that the Illinois fauna 

 differed in remarkable fashion from 

 that of the only other state for which it 

 was well known. New York. As a result, 

 it was necessary to practically revise the 

 entire North American fauna before the 

 Illinois groups could be satisfactorily 

 segregated to species. This was true espe- 

 cially in the family Hydropsychidae and 

 the so-called microcaddisflies, the Hydrop- 

 tilidae. As with the other aquatic groups, 

 an effort was made to rear the species and 

 associate larvae and pupae. Some of this 

 work was done with rearing cages, but 

 the greater part was accomplished by as- 

 sociating mature pupae with their corre- 

 sponding larval parts in the cocoon or 

 case. The report of the Illinois fauna of 

 this order, including keys to the adults 

 and immature stages, was published by 

 the Natural History Survey (Ross 1944). 



After this report appeared, some ac- 

 tivity relating to the Trichoptera was 

 continued, primarily centered around at- 

 tempts to reconstruct the origin of groups 

 and the dispersal patterns which led to 

 the formation of the present Illinois 

 fauna. As genera and families from other 

 parts of the world were studied, it was 

 possible to get a better understanding of 

 the classification and evolution of the or- 

 der. It is reminiscent of Malloch's and 

 Prison's work in the Diptera and Ple- 

 coptera that the immature stages were 

 found to hold the principal key to deduc- 

 ing the evolution of the group. These 

 studies made possible the publication of 

 the book Evolution and Classification of 

 the Mountain Caddisflies (Ross 1956). 



Goleoptera. — The beetles have fre- 

 quently been the subject of intensive study 

 by the Natural History Survey staff. 

 Early in the history of the organization, 

 extensive rearing was done, and volumes 

 of important information on this work 

 are scattered through the State Entomolo- 

 gist's reports. The first extensive Illinois 

 publication on the order was by Le Baron 

 (1874) who, in his fourth report as 



