ART. 9 TWO-WINGED FLIES OF TRIBE MILTOGRAMMINI ALL.EN 73 



approximated so that the height of this sclerite is distinctly less than 

 length of its wings. 



I have examined one puparium, finding the anal segment equipped 

 with several rows of sharply pointed, microscopic spines, and the 

 posterior spiracles located in a distinct pit (pi. 5, fig. 35) and sepa- 

 rated by a distance equal to diameter of one spiracle, 



P. fulvicorrds is common in the United States east of the Missis- 

 sippi River and is also known to occur in Colorado. It has been 

 reported from^ Oregon, but this record will very likely be found to 

 refer to P. pilosifrons or some other western species. 



The adults occur on barren, sandy ditch bottoms, over sand dunes, 

 on sand bars, barren places in open pastures, on stone-strewn country 

 roads and on the upper marine beach. In such places they are fre- 

 quently associated with several species of Senotainia and allied 

 genera as well as various species of fossorial Hymenoptera. They 

 have never been taken on flowers or rank vegetation. The adults 

 dart about just above the surface of the ground in characteristic 

 zigzag flight very closely resembling that of the small Larridae from 

 which they are not readily distinguished until they alight on the 

 ground. 



One adult was captured as it emerged from the burrow of a digger 

 w^asp, presumably one of the small Bembicidae which inhabit the 

 bea.ch in great numbers, at Mobile, Alabama. Another specimen 

 was reared from a puparium taken at Columbus, Ohio, where it was 

 found in damp sand, two or three inches from the surface and in 

 close proximity to nests of Bemhix spinolae. The writer formed the 

 opinion from the conditions under which the puparium was found 

 that the maggot had come to maturity in the nest of the Bembicid 

 and had crawled a short distance away into the loose sand to pupate, 

 but it is by no means certain that B. spinolae was the host of this 

 individual, since the tunnels of many small Larridae were present 

 in the same sand bed in close proximity to the nests of the Bem- 

 bicidae. Prof. J. B. Parker has made a very interesting observation 

 on a fly captured on the sand where a number of dift'erent species of 

 wasps were nesting, near Washington, D. C. (Parker note, No. 50). 

 He says that this species has the habit of wandering about over the 

 sand apparently engaged in smelling, and then in digging in the sand. 

 The specimen captured dug quite a pit at the entrance of a burrow 

 of Oxyhehis quadrinotatus Say, and then went through the motions 

 of oviposition in the pit. Professor Parker's observation is the 

 first to indicate the probable use to which the strongly flattened 

 fore tarsi of the females of North American species of Phrosinella 

 have become adapted. Coquillet ^^ records the rearing of an adult 



»« U. S. Bur. Ent., Tech. Ser., No. 7, p. 17, 1897. 

 54292—261- G 



