Swollen petiole, midrib, or stem...Neolasioptera vernoniae (Beutenmüller)

Swellings are green to red, 6–10 mm long. Hosts: V. baldwinii, V. noveboracensis

Cecidomyia? vernoniae sp. nov.

Gall.--Green, sometimes tinged with red, rounded or elongate, and of the texture of the stem of the plant. Inside it is soft, fleshy, and contains a single larva in an elongated narrow channel. Length about 7 to 12 mm; width 5 to 9 mm.

When dry the gall becomes brown and pithy inside and somewhat resembles a cherry-pit. It is usually situated on the mid-rib of the leaf of ironweed (Vernonia noveboracensis).

Habitat: NC, NY, IN

The gall is quite common during September, and the larvae overwinter and transform in the gall.

[as "Neolasioptera vernoniae"]:
...from stem galls on Vernonia noveboracensis ...

[as "Neolasioptera vernoniflorae"]:
Gall: an enlarged flower receptacle on Vernonia noveboracensis.

[gallformers.org follows the checklist of Gagné & Jaschhof (2021), which treats N. vernoniflorae as a synonym of N. vernoniae]