Article III. — A Preliniinary Clcissification of Diptcra, exclusive 

 of Pupipara, based upon Larval and Pupal Characters, mith Keys to 

 Imagines in certain Families. Part I. By J. R. M alloc h. 



Introduction 



Economic and taxonomic entomologists have long felt the need of 

 a synoptic treatise on the immature stages of Diptera. Owing to the 

 added impetus given to the study of this order by the comparatively 

 recent discovery of the economic importance of certain members of 

 the Diptera, the lack of available literature in English dealing with 

 the larvae and pupae has been considerably emphasized. It is not the 

 ijitention of the writer to attempt a definition of the larval and pupal 

 characters that may be depended upon invariably for the separation of 

 all the families of the order; a simple presentation of the main fea- 

 tures involved in the differentiation of the families, genera, and spe- 

 cies available to him is all that is attempted. It may be that these 

 characters will in the main, with necessary modifications, prove of 

 fundamental importance; but even if later they must needs be rele- 

 gated to the category of things that have been they will at least have 

 served the purpose for which they were intended — the identification 

 of a number of important economic groups — and also constitute step- 

 ping-stones to the firmer ground that can be reached only by a more 

 extended knowledge of the larvae and pupae, and by means of patient 

 and intelligent comparative examination of a larger amount of ma- 

 terial than is now at my command. 



1 have been requested by several of mv entomological colleagues 

 to undertake the task of presenting analytical keys to the immature 

 stages of Diptera, but for lack of material that would add to the infor- 

 mation already published I have hitherto refrained from doing so. I 

 have been steadily acquiring material, however, for over two years, 

 which, taken in conjimction with material previously in the collection 

 here and that kindly loaned me, probably includes more examples of 

 immature stages of Diptera as a basis for classification than have 

 been brought together elsewhere in the United States. It is, more- 

 over, my opinion that when any entomologist has a considerable 

 amount of additional information upon any phase of a subject it is 



