162 



incumbent upon him, in the interest of his fellow workers, to publish 

 not only his new data, be they new species or life histories, but inci- 

 dentally to link up with his data such facts already published as have 

 a direct bearing upon the subject in hand. It undoubtedly takes valu- 

 able time to make a comparative description of a new species, and 

 where several species in a genus require to be described it necessarily 

 means considerable work to the describer to make a synoptic key to 

 the whole genus as well as to give a description of each of the new 

 species. But when one considers that the time so spent is infinitesimal 

 as compared with that saved to subsequent workers who would other- 

 wise have to puzzle over descriptions in order to discover the differ- 

 entiating characters, it is evident that synopses and comparative de- 

 scriptions are not onlv useful but shtnild be regarded as indispensable 

 in scientific work. 



It is not with the intention of assisting the narrow specialist that 

 this paper is written ; the purpose is to enable the observant student 

 of nature and the economic entomologist to recognize those forms 

 that often come to their notice and thus obviate the frequent delays 

 and discouragements in obtaining information through other channels. 

 If this object is attained, even in a small measure, science will have 

 gained some advantage and the author will be satisfied. 



An effort has been made in the general discussions, and particu- 

 larly in connection with life histories, to avoid the use of pedantic 

 terminology, as the writer is of the opinion that except in formal de- 

 scriptions clarity of expression can be attained and conciseness com- 

 passed by the use of language that is understood by the non-entomo- 

 logical reader, much of the terminology and phraseology incessantly 

 cropping out in entomological publications being due either to the 

 training or the personal whim of the writers. 



This paper deals primarily with Illinois species, most of the 

 material used having been collected in the state by the various mem- 

 bers of the staff of the State Entomologist's Office or that of the State 

 Laboratory of Natural History. In a few cases, however, I have used 

 cxtralimital material belonging to our collections, and have also bor- 

 rowed examples of either larvae or of pupae, or of both, which were 

 not obtained in Illinois, in order to ascertain by an examination of 

 the specimens information not included in previously published de- 

 scriptions that would enable me to complete, as far as possible, data 

 upon certain genera or species. 



The classification adopted is essentially that used by Brauer in 

 1883*; but in detail I have not accepted his arrangement, nor have I 



*Denkschr. k. Akad. Wissenseh., Wien, math.-naturw. CI., 1883, pp. 1-100. 



