Forest Insect and Disease Newsletter

Don't look now, but your bark is missing

image: Aspen blothchminer moth

Aspen blotchminer.
Photo by Tom Murray

In locations where aspen blotchminers were abundant the previous summer, homeowners' calls with concerns about birds removing bark from conifers are common in late winter or early spring. The birds are feeding on the adults of the aspen blotchminers that have found shelter and overwintered under the bark flakes on conifers like jack pine and large white spruce trees. The birds are just flicking off the dead outer bark of the trees while searching for the moths. The coppery color of the exposed bark certainly gets homeowners' attention. The moths are very small, only about 4 mm long but occur in large numbers. Hundreds per square foot can sometimes be found hiding under house siding, trim, or other sheltered locations,including under barkflakes.

Aspen blotchminer larvae feed between the upper and lower leaf surface of quaking aspen leaves and create round or oval blisters. The larvae pupate in the leaf and the tiny moths everge and fly in August and search for sheltered sites to overwinter.

image: Pine bark

Exposed bark on a pine tree.

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Pine bark on the ground.

image: Aspen blotchminer damage to aspen leaf in late July

Aspen blotchminer damage
to aspen leaf in late July.

image: Aspen blotchminer omths on white sprice tree where bark was removed.

Aspen blotchminer moths on white spruce tree where bark flake was removed.