THE BEMBECID WASPS OF BOULDER COUNTY, 



COLORADO 



By S. A. Rohwer 



The Bembecids form a very distinct group of wasps, being easily 

 recognized by the sessile abdomen; three cubital cells, the second receiv- 

 ing both recurrent nervures; the labrum exserted beyond the clypeus; 

 the subtransverse head, and the subtle sculpture. Most of the Bem- 

 becids have very a wide range, but they are found more abundantly in 

 the warmer parts of the temperate zone. In color they vary very much, 

 as in the case of Stizus godmani Cam. The Colorado species were 

 recently tabulated by S. A. Johnson and S. A. Rohwer in the Entomo- 

 logical News (October, 1908, pp. 373-80); but since that paper was 

 written a few observations have been made which necessitate some 

 changes, and the notes on the habits of Bembex sayi Cress, and Stizus 

 godmani Cam. are of interest. 



The Boulder County species may be separated as follows : 



Middle tibiae with two spurs at the apex; ocelli normal; (metathorax emarginate posteri- 

 orly; small species) Stizus godmani Cam. 



Middle tibiae with one spur at the apex; anterior ocellus abnormal 1 



1. Metathorax emarginate posteriorly; (abdomen banded' with yellow; clypeus black) 



Bembidula ventralis Say. 



Metathorax not emarginate posteriorly 2 



2. Mesothorax above with two yellow lines; metathorax more or less yellow ... 3 

 Mesothorax above black; metathorax black 4 



3. Markings yellow; pleurae and pectus without black . . Steniolia duplicata Prov. 

 Markings greenish-yellow; pleurae and pectus with black . . . Bembex sayi Cress. 



4. First abdominal segment with two broad spots which nearly meet in the middle; scutel- 



lums black Bembex spinolae Farg. 



First abdominal segment with four pale spots, the two middle ones smaller and farther 

 posterior than the lateral ones; scutellums maculated . . Steniolia obliqua Cress. 



Steniolia obliqua Cresson 

 This species has been found at Ward, Colo., July, 1905, at flowers 

 of Gilia by Professor T. D. A. Cockerell; and at Boulder, Colo., Sep- 

 tember 8, 1908 (S. A. Rohwer). 



243 



