The Zimmerman Pine Moth is a destructive pest that attacks several Pine varieties in the Chicago area. Preferred hosts are Austrian and Scotch Pine trees, but Eastern White and Mugo Pines are also attacked. The Zimmerman Pine Moth spends the winter as a young caterpillar, underneath the bark of its host.  Starting in mid to late April (depending on weather conditions), the larvae begin to move to the base of tree branches and burrow inside. The larvae feed inside the tree until late July or August. The tunneling larvae create masses of pitch in tree branch whorls. In late July and August, adult moths emerge from the host tree and fly to tree wounds or pre-existing pitch masses to lay eggs. These eggs hatch and feed for a short period of time, before preparing to overwinter on the host tree.

There are a few visual indicators that a Pine tree has a Zimmerman Pine Moth infestation. Look for masses of pitch formed on the tree trunk. The Zimmerman Pine Moth larvae are about one inch in length and whitish to light gray in color. The larvae can only be found in the pitch masses, under the tree bark or in new tree shoots. The adult Zimmerman Pine Moth is gray, with zigzags on their reddish brown wings. The adult moths are only seen in late summer. Because the indicators may be overlooked, it’s advisable to have a Certified Arborist inspect the tree to verify a possible infestation.

Pine trees that suffer from infestation year after year will experience major branch breakage and will become a much weaker tree. Oftentimes, the tunneling moth larvae will weaken the trunk so severely, the trunk snaps off just a few feet above the ground. This may not kill the Pine tree, but it will result in a multi-trunked and much shorter, broader tree.

Controlling or avoiding a Zimmerman Pine Moth infestation requires knowledge of the insect’s life cycle. Pesticide application should occur when the Zimmerman Pine Moth is most susceptible to treatment. Ordinarily, treatment involves a series of pesticide applications that target the insect when it’s most vulnerable. Contact pesticides are most effective in early spring, when the larvae is moving on the tree and haven’t yet burrowed inside the tree and in late summer, when the adult moths emerge from the tree.

The Plant Health Care Department carefully monitors Zimmerman Pine Moth movement to ensure treatment applications are given at the appropriate times. If you’ve received Zimmerman Pine Moth treatment recommendations from KTS or would like more information on available options, call the PHC Department today. We have not yet begun 2013 applications.

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