ocellate gall midge

not listed

not listed

not listed

Ocellate gall midge is a very small fly. It occurs in the United States and southern Canada east of the Great Plains. In Minnesota it occurs in the forested eastern half of the state but is absent from the west.

The larva produces a flat, 5 ⁄16″ to ⅜″ in diameter gall on the upper surface of a red maple leaf. The gall is a yellow or greenish-yellow “eyespot” bordered by a ring with a red inner edge and a purple outer edge. The center of the spot is slightly raised and may be green, yellow, red, or purple. The larva is unprotected in the depressed center of the spot on the underside of the leaf.

Total length: 5 ⁄16″ to ⅜″

Septoria Leaf Spot (Septoria aceris) is a fungus that produces similar dark brown or tan spots with light brown centers. Black fungal bodies are visible on the upperside of the leaf under magnification.

red maple (Acer rubrum var. rubrum)

One generation: May

Spots: Spring to fall

The female deposits eggs singly on the underside of red maple leaves. After the larva hatches it feeds on the leaf and injects a hormone which causes the leaf to produce a gall. It spends 8 to 10 days on the leaf, growing to a size of about 1 ⁄16″ in length. It then drops off and burrows into the ground. It overwinters in the ground as a pupa and emerges as an adult early May the following year.

The larva feeds on the leaf at the center of the spot on the underside of the leaf.

Sources

7, 24, 27, 29, 30, 82.

Larva

Gall

Leaf

Location: Albany, NY