Pontania pisum

Nematus salicis pisum
Nematus quercicola
Nematus pisum

"Gall. — The gall made by it is found on Salix discolor. A subspherical, pea-like, hollow, pale yellowish-green gall, always growing on the underside of the leaf and almost always from one of the side veins (in one case from the midrib), and attached to the leaf by only a minute portion of its surface; 0.18 to 0.28 inch in diameter, and a few, immature, only 0.08 inch 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 little shriveled, generally studded in the medium-sized ones with four to twelve small, robustly conical nipples, which in the larger ones have burst into a scabrous blown scar. Only in three out of sixty-two was there any rosy cheek, as in S. pomum. The point of attachment is marked on the upper side of the leaf by a brown subhemispherical depression.

Range: IL, NY

- Charles Lester Marlatt: (1896) Revision of the Nematina of North America, a Sub-family of Leaf-feeding Hymenoptera of the Family Tenthredinidae^©

Reference: https://www.biodiversitylibrary.org/page/52142981#page/114/mode/1up