Birch skeletonizer

Distribution

Canada

Micro-habitat(s)

Leaf

Damage, symptoms and biology

In summer and fall, skeletonized leaves and small, oval-shaped white silken moulting webs on the undersurface of leaves are easy-to-recognize signs of the birch skeletonizer’s presence.

After hatching, the young larvae enter the leaves and feed as miners. At about the midpoint of their larval development, they emerge from the mines to feed on the undersurface of the leaves. During heavy infestations, the leaves become completely skeletonized; they dry out and turn brown between late August and early September and drop prematurely.

Life cycle (East of the Rockies)

Other information

Birch skeletonizer is native to North America and has a transcontinental distribution. In Canada, outbreaks are cyclical, occurring every 9 to 10 years. Eight separate outbreaks have been reported in eastern Canada since the end of the 19th century. Over a period of 3 to 5 years, the population grows rapidly and invades extensive regions. A few years later, the population drops back down to an endemic level.

To minimize damage to isolated trees, the foliage and plant debris at the base of affected trees should be collected and burned in late fall or early spring. This will destroy the pupae.

Main host(s)

Grey birch, white birch, yellow birch