- The most colorful and noticeable of the eyespot galls (see above photo) occur on red maple. They may also attack silver, striped, and sugar maples.
- The spots are 8-10 mm in diameter.
- Eyespot galls are caused by a gall midge that rarely causes injury.
- The adult is a small midge. It emerges from the soil in the spring and lays its eggs in the leaf tissue on the undersides of leaves. As the larva grows, the leaf tissue surrounding it swells slightly and the plant develops red and yellow rings around the gall.
- The color is most intense in June and later turns brown.
- The larva completes its development in 8-10 days, it then drops to the ground, burrows into the soil and pupates. There is one generation a year.
Tulip tree (Liriodendron tulipifera) gall
Tulip tree leaf spot gall. Photo: Lance S. Risley, William Paterson University, Bugwood.org
- Another species of midge causes a gall on tulip tree leaves.
- The tulip tree spot gall is brown and resembles a fungal leaf spot.
- As the spots age, the tissue may drop out leaving a hole in the leaf.
- The spots are 4-7mm in diameter.
- The life cycle is similar to the eyespot gall midge of maple, but there are several generations per year.
- No control necessary.
- These gall midges rarely cause injury even though they disfigure leaves.