DESCRIPTIONS OF LARVAE AND PUPAE OF TWO- 

 WIXGED FLIES BELONGING TO THE FAMILY 

 LEPTIDAE 



By Charles T. Greene 



Of the Bureau of Entomology, United States Department of Agrictilturc 



This paper contains descriptions of 7 species of larvae and 11 

 species of pupae of flies belonging to the dipterous family Leptidae, 

 It is based on a study of the material representing larvae and pupae 

 of this family in the collections of the United States National 

 Museum, supplemented by certain specimens which have kindly been 

 lent to me by C. W. Johnson, of the Boston Society of Natural 

 History. The specimens used in this paper are labeled with the 

 number herein given to the species and with a reference to the num- 

 ber of this article. 



Various authors have divided the group as here treated into three 

 families — Leptidae, Xylophagidae, and Coenomyidae — but after a 

 careful study of the immature stages I am convinced that they rep- 

 resent only one family group, and to this the name Leptidae should 

 be applied. In my studies of the immature stages of Diptera I 

 have found that the form of the spiracle in the pupa is constant for 

 each family. Should this group be divisible into three families one 

 would expect to find three distinct forms of spiracles, but in the 

 material available only one type occurs, which very stronglj'' con- 

 firms my impression that these insects do not belong to more than 

 one family. 



The adults of the family Leptidae vary in size from small to 

 large and robust species. Their flight is rather slow, and the major- 

 ity of them are found flying about foliage along the edge of woods 

 and shady places. Some few species, however, are frequently found 

 resting on tree trunks or old logs. The species of the genera Rhach- 

 icerus, Xylomyia, and Xylofliagus very closely resemble certain 

 ichneumon flies belonging to the order Hymenoptera. None of the 

 adults of this family are injurious to man, although many species 

 of the genus Symqjhoromyia are annoying, because they persistently 

 fly about the heads of men and animals, and one or two species have 

 been reported as actually sucking the blood. The habits of the 

 larvae are varied. Many are predacious and some are scavengers. 



No. 2651. — Proceedings U. s. National Museum, Vol. 70, Art. 2. 



3061—26 1 



