Gall. Length 2 to 4 mm, shining and often reddish. It is a fleshy fold near the mid vein, frequently producing curling or even recurving of the leaf. (Plate 9, figure 3.) One or more larvae inhabit the deformity

Swollen vein, causing severe leaf distortion ... Janetiella asplenifolia (Felt)
Midveins are folded, fleshy, reddish, and cause extreme folding of the leaf. Larvae are gregarious. Host: [Myrica] asplenifolia [=Comptonia peregrina]...