AMERICAN HYMENOPTERA. 217 



bles, black. Clypcus emarginate iu an arc of about 90°. Labrum 

 rounded at tip. The sutures of occiput back of ocelli black, the ele- 

 vated trapezoidal space rarely occupied by a black cloud. Antennse 

 one-half as long as the body, joints 3 — 5 subequal, 9th generally as 

 long as 8th, the scape black, the flagelluni brown-black, its terminal 

 half often tinged beneath with rufous. Mesothorax always with an ob- 

 scure subquadrate spot at the intersection of its sutures, and a more 

 definite longer one on the anterior half of the anterior lobe, the two of- 

 ten confluent; the tip of scutel sometimes and always the entire meta- 

 thorax, including the basal plates, black, very rarely the entire meso- 

 thorax is black. Pectus immaculate, except in one dark 9 , is slightly 

 obfuscated. Tergum, with sometimes the basal edge of first segment 

 only, black, and all the sutures toward the base dusky ; usually with 

 more or less of its basal half black, rarely with the whole or nearly its 

 whole surface black or blackish ; venter always immaculate, lateral 

 plates very rarely ( 9 ) basally black. Ovipositor honey-yellow, its 

 sheaths black, l^egs honey-yellow ; coxae and trochanters of the two 

 anterior pair more or less whitish, tips of all six tarsi lightly obfuscated 

 and sometimes the extreme tips of hinder tibias. AVings hyaline, veins 

 black, costa honey-yellow, base of stigma honey-yellow. Third sub- 

 marginal cell usually longer than wide, sometimes equal, very rarely or 

 only in a single wing three or four times wider than long or obsolete. 



% . Differs from 9 only as follows : The quadrate spot on vertex is 

 larger and often more or less confluent with the eyes, and never sepa- 

 rated but by a capillary orbit. The occiput, except a narrow orbit, 

 black. Antennae two-thirds as long as body, almost invariably dull ru- 

 fous above, or bright rufous or pale green beneath, except toward the 

 base, very rarely as in 9 . The entire thorax black, except the tegu- 

 Ue and two edges of anterior angle. Tergum black, sometimes 1, or I 

 and 5, or two or three terminal segments slightly tipped with yellow; 

 lateral plates clouded, especially towards base, venter immaculate. Cos- 

 ta scarcely pale, only extreme base of stigma whitish. 



Twenty-six % and forty-six 9 bred April 16 — 25. The gall S. 

 pomum found on Salix cordata and very rarely on S. discolor. A 

 smooth, fleshy, sessile, globular or slightly oval monothalamous gall, 

 like a minature apple, 0.30 — .55 inch diameter, growing on one side 

 of ths midrib of a leaf, and extending to its edge or beyond it. The 

 principal part of the gall projects from the under side of the leaf; very 

 rarely it is bisected by the leaf. Color greenish-yellow, sometimes 

 with a rosy cheek, especially the upper surface, and often with little 



TK.^.NS. AMER. ENT, SOC. (28) AUGUST, 1867. 



