Andricus piperoides, n. sp.

Galls from one-eighth to three-eighths of an inch in diameter, in dense clusters along the mid-vein of full grown red oak leaves (Quercus rubra). They are found only on the largest leaves of the thriftiest shoots of young oaks. The clusters contain from one or two dozen galls up to a hundred or more, and extend along the vein two, three or even four inches. The vein is considerably enlarged, and is often split by the crowding of the galls as they increase in size. The blade of the leaf is often torn by the same force and the galls appear on both surfaces. When on the tree they are covered with a dense, coarse pubescence which is, in color, a dusky drab, or when exposed to the sun a brownish red. They are round except a very slight elongation at the point of attachment to the leaf. After falling to the ground they soon turn black, and after losing their pubescence they resemble quite closely small black pepper corns. At this time they are a solid mass of vegetable cells with a minute jelly-like center, which is the undeveloped larva. The growing larva devours the gall till at maturity nothing remains but a thin shell.

My galls were collected in October and were kept until late the next Summer under conditions as nearly normal as possible. As the flies seemed mature in August I placed the galls in dry boxes, expecting the insects would soon appear.

During October and November I removed from the galls some two hundred insects. They were somewhat torpid but seemingly mature. These were alive in January of the next year, and those in the galls had undergone no change. A few individuals emerged from the galls in the Winter, though most remained alive in the galls many months after.

- HF Bassett: (1900) New Species of North American Cynipidae (1900)^©

Reference: https://www.biodiversitylibrary.org/page/7522373#page/338/mode/1up