Dormant oil in late winter or early spring smothers the adults but it is too late for that now. Ultra-fine or superior oil is a product that can be used to smother insects during the growing season without damaging most plants. Look for the tiny yellow circular spots on newly emerging birch leaves which indicate feeding of the birch leaf miner. This early generation of the insect causes stress on the tree that can render it more susceptible to a more serious pest, bronze birch borer. Several different pesticides can be used to control it.
Merit can be soil injected in the fall.
Di-syston granules can be placed in holes punched into the rootzone in early spring. Or one of several chemicals can be sprayed onto the leaves when the spots are first seen. Fourth Week Transplant to the garden now plants of Brussels sprouts, late cabbage, cucumber, and melons. Seeds of summer and winter squash and cucumber may be sown directly into the garden. Tuberous begonia, dahlia, canna, and caladium plants may be transplanted outdoors.