319 



by the fact that the legs are whitish and the fifth 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 

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

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

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

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

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

 itages 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 

 'ffice of the State Entomologist for identification, and quite often it 

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

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

 re comparatively little known, and very often entomologists who have 

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

 ^ct to make descriptions that will serve to identify the species in those 

 tages upon any subsequent occasion ; or the written description or 

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

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

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

 een reared by members of the ofiice staff here or by himself, and to 

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

 I ludents to recognize the species when occasion arises. 

 I Of the species described herein, Psilocephala hccnwrrhoidalis Mac- 

 Liart is predaceous on wireworms, while the species of Asilidce and 

 [ydaidcu are also predaceous upon subterranean larvae, and are of 

 Dnsiderable economic importance. The species of Mydaidcc is preda- 

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

 ombyliida: dealt with are parasites, those of Anthrax being recorded 

 > internal parasites upon Lepidoptera; Bxoprosopa fascipennis is 

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

 achnosterna spp. ; Spogostylum anale and Sparnopolius fulviis are 

 toparasitic upon larvae of Cincindela and Lachnosterna respectively, 

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

 ■cord is available that indicates whether fascipennis is an internal or 

 eternal parasite. The species of Mycetophilidcc described, Mycetohia 

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



