319 



by the fact that the legs are whitish and the fiftii joint of all tarsi deep 

 black. The other six species all have a greater proportion of the 

 legs blackened. 



I had a slight doubt about the identity of this sex as the male of 

 pallida when I wrote the description, but since then I have examined 

 a series of both sexes which were reared by Mr. R. A. Muttkowski 

 from larvae obtained in Wisconsin, and find that despite the unusual 

 difference in color it is undoubtedly the male of pallida. I understand 

 from Mr. Muttkowski that he is preparing descriptions of the early 

 stages of this and several other species for publication. 



Immature Stages of some Illinois Diptera, 

 AND Biological Notes 



Not infrequently larvae or pupae of Diptera are submitted to the 

 office of the State Entomologist for identification, and ciuite often it 

 has been impossible for those in charge of this branch of the work to 

 give names for the species involved. The immature stages of Diptera 

 are comparatively little known, and very often entomologists who have 

 succeeded in rearing species from either the larval or pupal stage neg- 

 lect to make descriptions that will serve to identify the species in those 

 stages upon any subsec|uent occasion; or the written description or 

 figures are so inaccurate or vague that they serve only to give a gen- 

 eral idea of the appearance of the species. It is the purpose of the 

 present writer to describe in detail a number of species which have 

 been reared by members of the office staff here or by himself, and to 

 figure the principal features of each so that it may be possible for 

 students to recognize the species when occasion arises. 



Of the species described herein, Psiloccphala hccmorrhoidalis Mac- 

 quart is predaceous on wireworms, while the species of Asilidcc and 

 Mydaidcc are also predaceous upon subterranean larvae, and are of 

 considerable economic importance. The species of MydaidcE is preda- 

 ceous upon larvae which burrow in rotten tree-stumps. The species of 

 Bonihyliidcc dealt with are parasites, those of Anthrax being recorded 

 as internal parasites upon Lepidoptcra; Bxoprosopa fascipennis is 

 parasitic upon Tiphia spp., which are themselves parasitic in larvae of 

 Lachnosterna spp. ; Spogostylum anale and Sparnopolius fidvus are 

 ectoparasitic upon larvae of Cincindcla and Lachnosterna respectively. 

 The habits of Bxoprosopa fasciata are not known to me, while no 

 record is available that indicates whether fascipennis is an internal or 

 external parasite. The species of Mycetophilidcc described, Mycetobia 

 divergens, has been recorded as attacking the trunks of fruit trees, but 



