How to check your trees for invasive 'drilling beetle' in Michigan

Imagine what the summer heat would feel like without the cooling shade of your backyard trees. If you appreciate your trees, August is the time to show them how much you care.

Take a few minutes to check your trees for Asian longhorned beetles and the damage their larvae leave behind.

“August is Tree Check Month – the best time to spot the round, drill-like holes made by the Asian longhorned beetle,” said Jeff Zimmer, acting director of the Michigan Department of Agriculture and Rural Development's Pesticide and Plant Pest Management Division. “These destructive pests have invaded areas of Ohio, New York and Massachusetts, causing the removal of over 180,000 trees. In order to prevent this in Michigan, we are asking everyone to look for and report signs of the Asian longhorned beetle.”

The Asian longhorned beetle is on Michigan’s invasive species watch list because it poses an immediate or potential threat to the state's economy, environment or human health.

What to look for

Checking your trees is important because early detection of the Asian longhorned beetle can save hundreds to thousands of trees. This beetle affects many common deciduous trees, such as maples, birch, willow and others. So what should you look for?

  • Dime-sized, perfectly round, beetle exit holes in the trunk or branches.
  • Shallow chew marks in the bark, where the beetle lays its egg.
  • Sawdust-like material at the base of the tree, or where branches meet the trunk.
  • Dead branches on otherwise leafy trees.
  • Large (1 inch to 1 1/2 inches long), shiny black beetles with white spots and white striped antennae.

Check for look-alikes

A similar beetle native to Michigan is often mistaken for the Asian longhorned beetle.

The white spotted pine sawyer has a distinctive white spot below the base of its head – between the tops of its wing covers. This and its brown or dull black color distinguish the sawyer from the Asian longhorned beetle.

What to do

If you see signs of Asian longhorned beetle damage, or the beetle itself, follow these steps:

  • Make note of what was found and where. Take a photo, if possible.
  • Try to capture the insect, place it in a container and freeze it. This will preserve it for easier identification.
  • Report findings as soon as possible to the U.S. Department of Agriculture by calling 866-702-9938 or completing an online form at
  • Reports also can be made to the Michigan Department of Agriculture and Rural Development at 800-292-3939 or

For more information on the Asian longhorned beetle, visit

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