Look for the development of pod galls as leaflets expand. There are several generations a year. The dainty adult flies become active at budbreak, laying their eggs in developing leaflets.
New adults emerge from the galls, laying eggs of subsequent generations.
Destruction of pod galls that fall to the ground can reduce the midge population. When midges are present in high numbers, a residual insecticide applied at budbeak may be effective. Drooz, A.T. 1985. Insects of Eastern Forests . USDA Forest Service Miscellaneous Publication 1426.