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)
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.
Canadian Forest Service Publications
Diet and feeding behaviour
: Feeds on the leaves of plants.
- Skeletonizer: Devours the upper layer of leaves but not the veins, thus producing a skeletal appearance.
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