Birch Leafminer

SYMPTOMS: Brown leaves, hollowed out, with black particles inside hollowed leaves.

LIFECYCLE: The flying adult lays eggs on birch leaves in spring when young leaves are beginning to unfurl. The eggs hatch within a few days. The hatchling larvae begin to feed on the tender new leaves by burrowing into the leaf, leaving the outer walls of the leaf intact. This appears as a brown blistered area. The mature larvae eventually emerge from the leaf and fall to the ground where they pupate (transform) into the flying adult. This flying adult then returns to the leaves of the birch and lays more eggs on areas of new growth, starting the cycle over again. This cycle may repeat two or three times during the growing season.

CONTROL: Once the larvae have entered the leaves, it is very hard to kill them. Spray with Bayer Tree & Shrub Spray early in the spring as the young leaves are beginning to unfurl. Spray again in early July and again in mid to late July to control the second and third generations. Systemic insecticide that enters the tree through the root system and permeates the entire plant is also an effective control. This should be applied early in April, and again at the beginning of July.

NOTE: Read and understand the rates of application printed on the manufacturers’ label. Follow these directions for safety and effectiveness.