ART. '.\ TWO-WIXGKD FI.IES OF TRIBE MILTOGRAMMINI ALLEN 27 



cluiracters are as follows: Spermathecal ducts not united, their basal 

 halves conspicuously inflated; accessory glands of equal size, elongate, 

 more than ten times length of their ducts. In the uterine pouch of 

 one, 15 large maggots were counted. With the maggots in the 

 pouches occurred the larval sheaths, evidently sloughed off by the 

 larvae as soon as they became active in the uterus. The sheath 

 was reticulated, more conspicuously so in a belt about the middle. 

 Uterine maggots in the specimens dissected were all at about the 

 same stage of development. 



Several first instar uterine maggots have been examined. In the 

 buccopharyngeal apparatus (pi. 5, fig. 33) were found the only 

 readily recognized specific characters. The median hook is broad to 

 the middle, thence suddenly constricted to a fine, slightly curved 

 point, ventral tooth lacking; lateral hooks moderately curved but 

 not definitely hooked. 



The puparium (pi. 4, fig. 21) is chestnut-brown in color, with 

 minute, backwardly directed spines encircling the anterior part of the 

 first five segments; and occurring ventrally on the remainder of the 

 segments. In lateral view; broadest caudad of the middle, tapering 

 shghtly towards the front, abruptly behind; dorsal margin convex, 

 ventral straight or even slightly concave in the middle. Anterior 

 spiracle with four or five papillae. Anal depression as in rubriventris 

 but distinctly deeper than in trilineata. 



Specimens have been examined from Massachusetts, Ohio, District 

 of Columbia, Maryland, and Mississippi. In the Canadian national 

 collection there are several specimens from Vernon, British Columbia, 

 Onah and Aweme, Manitoba. The habitat of vigilans appears to be 

 more restricted than that of some of the more common species of the 

 genus. In Mississippi, specimens were taken on the sides of a shady 

 road, in the "flat woods" predominated by short leaf pine in mixture 

 with hardwoods. In Ohio, a puparium was dug from a small sand 

 deposit on a wooded river bank. Adults have not been taken on 

 flowers. 



The biology oi vigilans is hnked with that of two species of Bicyrtes, 

 quadrifasciata from which it has been reared and ventralis Say, from 

 whose burrow the female fly has been captured, and with Bemhix 

 spinolae. All three wasps belong to the sand burrowing Bcmbicidae. 

 Both species of Bicyrtes stock their cells with Hemiptera, while 

 Bemhix spinolae provisions its nest with Muscoid flies. 



Prof. J. B. Parker in 1914, at Washington, D. C, captured a female 

 emerging from the nest of Bicyrtes ventralis and another female coming 

 out of a burrow of Bemhix spinolae}'^ 



S. vigilans was also noted in the field during July, 1922 by M. R. 

 Smith who found the flies associated with wasps in a colony of B. 



1' Allen, Occ. Pap. Bost. Soc. Nat. Hist., vol. 5, p. 90. 



