204 EDWARD NORTON. 



21. N. 8. pisum. 



Ncmatus s. pisum, Walsli, Proc. Ent. Soc. Phil, vi, ISfifi, 259. 

 Length 9, O.ll— .14; %, 0.22— .26 inch. Br. wing 9,0.13— .17,; %, 0.1.3— 

 .14 inch. 



" 9 . Shilling greenish-white. A cjuiidrate spot enclosing the ocelli, 

 and extending behind onto the disk of the occiput, but not reaching 

 the antennjie nor the eyes, a dot above the origin of the antenn;ie and 

 tips of the mandibles black. Clypeus deeply euiarginate. Labrum 

 rounded at tip. Antennjxi three-fifths as long as body ; joints 3 — 5 

 subequal, the scape black, the flagellum brown-black. Thorax black, 

 with the teguloe, and anterior angle, except its lower angle, greenish- 

 white. Abdomen black, with the venter and the tip of dorsal segment 

 8, and its side-plates indistinctly pale. Cerci whitish, dark-tipped. 

 Legs pale greenish-white, the tarsal tips, especially in the hinder legs. 

 and the tips of their tibice fuscous. Wings hyaline, veins black, stig- 

 ma fuscous. 



% . Differs only from female in having larger black sjiots upon the 

 venter and occiput and only two edges of anterior angle pale. The an- 

 tennoe are four-fifths the length of body, the scape black, the flagellum 

 brown-black above, palpi dull green beneath, upper and hind margin 

 of collar pale. 



The gall made by it is found on Salix discolor. A subspherieal, pea- 

 like, hollow, pale yellowish-green gall, always growing on the under 

 side of the leaf and almost always from one of the side-veins, in one 

 case from the main rib, and attached to the leaf by only a minute por- 

 tion of its surface, 0.18 — .28 inch in diameter, and a few, immature, 

 only .08 in diameter. Almost invariably there is but one gall to the leaf, 

 but on four leaves there were two, and occasionally two are confluent. 

 Surface in some smooth and even, without pubescence, in others a lit- 

 tle shrivelled, generafly studded in the medium-sized ones with four to 

 twelve small, robustly conical nipples, which in the larger ones have 

 burst into a scabrous brown scar. Only in three out of sixty-two was 

 there any rosy cheek, as in S. pomnm. The point of attachment is 

 marked on the upper side of the leaf by a brown sub-heuiispherical de- 

 pression. 



Larva. — August 25th, apparently eighteen-footed, no an.il prolegs 

 being visible. When at rest it elevated its entire abdomen behind the 

 true legs in the air. Length 0.17 — .2o inch ; color whitish hyaline; 

 head slightly dusky ; mouth dusky; eye spots circular and black; an- 

 al segment et^ual in length to two of the others and apparently divided 

 iu two by a transverse medial suture. The larva goes under ground to 



