62 PROCEEDINGS OF THE NATIONAL MUSEUM vol.79 



Male. — Length 3 mm., colors black and yellow ; back of head, ver- 

 tex, cheeks in part behind, malar space entirely on one specimen, and 

 forehead in part, black; one specimen with pronotum yellow brown 

 only on front lateral corner, as on typical black occidentalism but en- 

 tire side and the anterior lateral portion of upper surface of pro- 

 notum yellow on the other specimen ; mesopleura black on one speci- 

 men but lower third of scapulae, and upper portion of mesopleura 

 yellow on the other; legs of lighter-colored specimen with bases of 

 front and middle coxae, and all of hind coxae, black, femora and 

 tibiae of all legs with at least middle of outer surfaces narrowly black, 

 legs otherwise yellow, except tarsi, which are stramineous, the other 

 specimen with legs dark as on typical specimens of occidentaUs ; 

 venter of abdomen yellow. 



Type locality. — Prescott, Ariz. 



ry/?^.— Male, U.S.N.M. No. 42268. 



Reinarhs. — Described from the type and a male paratype, both 

 in the National Museum and from the type locality. They were 

 reared by L. H. Weld, May 15 and August 17, 1918, from undeter- 

 mined galls on an evergreen oak {Quercus grisea or arizonica). The 

 type issued on the latter date. Both individuals are labeled " Hopk. 

 U. S. 15604^" 



24. DECATOMA NIGRICEPS Walsh 



Plate 2, Fiquke 22 



Decatoma nigriceps Walsh, Amer. Eiit. and Bot., vol. 2, no. 10, pp. 300, 301,, 

 1870. 



Perhaps nearest to occide^italis Balduf, from which it may be dis- 

 tinguished by the differences enumerated before the description of" 

 that species. 



Female. — Length 1.8 to 2.2 mm., mostly black with greatly vari- 

 able degrees of yellow; head black, except a narrow circumocular 

 yellowish-brown band with sometimes an oblique wedge-shaped, 

 branch extending forward from it on the vertex toward the an- 

 tennal scrobe, lateral margins of scrobe usually, oral area more- 

 or less, in some specimens a band extending upward from oral 

 region to each antennal fossa and in others to the malar space nar- 

 rowly, yellowish brown, and a few specimens have the head yellow 

 except the vertex and the forehead; palpi whitish; scape entirely 

 honey yellow, pedicel yellowish beneath, light brown above, flagel- 

 lum medium to dark brown; pronotum black but anterior lateral 

 corners always, and sometimes the side more or less, dull yellow, in 

 some specimens all the anterior margin of the segment dull yellow, 

 in others only the mesal third of the upper surface black, with front 

 margin yellow; mesothorax black, lower part or all of scapulae and* 



