319 



l)y the fact that the legs are whitish and the fiftli joint of all tarsi deep 

 hiack. 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, l)ut since then I have examined 

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

 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 quite 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 subsequent 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, Psilocephala hcumorrhoidalis Mac- 

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

 Mydaidcc are also predaceous upon subterranean larvae, and are of 

 considerable economic importance. The species of Mydaidcc is preda- 

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

 BomhyliidcE dealt with are parasites, those of AntJirax being recorded 

 as internal parasites upon Lepidoptcra; Bxoprosopa fascipcnnis is 

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

 Lachnosterna spp. ; Spogostylmn anale and Sparnopoliiis fidvus are 

 ectoparasitic upon larvce of Cincindela and Lachnosterna respectively. 

 The habits of Bxoprosopa fascia ta are not known to me, w^hile no 

 record is available that indicates whether fascipcnnis is an internal or 

 external parasite. The species of Mycctophilidcc described, Mycetobia 

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



