Zimmerman Pine Moth

Austrian, Scots and Red Pines are beautiful, dense trees that help protect your landscape. These trees can also be extremely susceptible to a pest called the Zimmerman Pine Moth (ZPM).

When are my trees at risk and what should I look for?

White, tan or rust colored resin flowing down the trunks of Austrian, Scots and Red pines can indicate an infestation of ZPM caterpillars. Large numbers of these small caterpillars bore into the trunks of pines, causing the tree to weaken and become more susceptible to wind damage. Heavy infestations of ZPM impart a unsightly appearance on the trunk and can cause stress to the tree. One or two boring points on the trunk cause little concern to the tree’s health. However, as the infestation multiplies, these attacks should be treated immediately.

The ZPM overwinters as a small caterpillar in a silken cocoon-like structure under the bark scales. In early spring, the caterpillars will begin to feed on the bark and later will tunnel into lateral or terminal shoots or directly into the main trunk.

The caterpillars remain inside the main trunk until they complete development. By mid-summer, the caterpillars pupate inside the external resin flows they leave behind or within their tunnels. Adult ZPM will emerge as small gray/brown moths with banded wings.

Maintaining tree health is always an important part of any pest management program. Contact your local arborist to create a prevention or treatment plan for your unique landscape. You can also view the full PDF here.

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