The ocellate gall midge causes an ocellate (single-spotted), pale green to yellow, often bright red-margined gall. This creep is most often found on red maples. Galls appear in May and contain a single larva. After the larva matures it falls to the ground, and over-winters as a pupa. In spring it appears to mate, and a new round of galls is formed. These creeps are something to look at, and don’t cause much harm to the tree at all.
To learn more, check out this site:http://ipm.ncsu.edu/current_ipm/13PestNews/13News4/pestnews.pdf