2 U.S. NATIONAL MUSEUM BULLETIN 2 68 



Structural Characters 



The genus Eucerceris which is limited to North America may be 

 distinguished from the more widely distributed genus Cerceris by 

 the following structural characters : 



(1) The 3rd submarginal cell of the fore wing is more or less in- 

 flated in Eucerceris and the second submarginal cell is not always 

 petiolate as in Cerceris. 



(2) The hair lobes of the male clypeus are less distinctly separated 

 from the other setae of the lower face and are never "waxed" as is 

 so true of Cerceris. 



(3) The terga of Eucerceris show a more or less distinct mesal 

 depression in which the punctation is crowded. This depressed area 

 is inclined to be darker than the convex surfaces of the terga. 



(4) The male pygidium of Eucerceris differs markedly from that 

 of the female and shows distinct lateral denticles. 



The genotype of Eucerceris was designated as Eucerceris fulvipes 

 Cresson by V. S. L. Pate (1937, p. 27). 



Biological Studies 



Very little is yet known about the biology of most species of Eucer- 

 ceris. In the writer's 1939 publication Eucerceris jiavocincta Cresson 

 was recorded as collecting Dyslobus lecontei Casey at Breitenbush 

 Hot Springs in Marion County, Oreg. Bohart and Powell (1956) 

 reported E. jiavocincta Cr. as carrying in an undescribed species of 

 Dyslobus. Linsley and MacSwain (1954) report E. ruficeps ScuUen 

 using the weevils Dysticheus rotundicollis Van Dyke and Sitona 

 californicus Fahrens in the sand dune region east of Antioch on the 

 lower San Jaquine River. Ejombein (1960a, b) reported E. triciliata 

 (now known to be E. pimarum Rohwer, ScuUen, 1965) as taking the 

 weevil, Minyomerus languidus Horn near Portal, Ariz. E. rubripes 

 Cresson was found by Mont A. Cazier collecting a species of weevil, 

 Peritaxia sp., 2 mi. NE. of Portal, Ariz., July 28, 1961. 



Acknowledgments 



Material studied in the preparation of this pubhcation has come 

 from most of the insect collections found on this continent and several 

 European institutions as mentioned in the author's publication on 

 Cerceris north of the Mexican border (Scullen, 1965b). Also, many 

 individual collectors have contributed to these studies as mentioned 

 in the above-cited publication. The drawings in this pubhcation 



