The Michigan DNR wants people to start checking trees for adult Asian longhorned beetles.
That’s because August is the most likely time to see the beetle and the damage it causes to trees.
Checking for the beetle and the damage it leaves behind is one way you can protect trees and fight an invasive species. Michigan officials are asking residents to take 10 minutes this month to check trees around their homes.
Although the beetle has not yet been discovered in Michigan, officials say it’s “crucial we keep an eye out for it.” Discovering early signs of infestation can prevent widespread damage to the state’s forest resources, urban landscapes and maple syrup production.
What is the Asian longhorned beetle (ALB)?
It’s an invasive wood-boring beetle that attacks 12 types of hardwood trees, including maples, elms, horse chestnuts, birches and willows. It doesn’t have any predators or diseases to keep the population down.
When it’s in its larval stage, it feeds inside tree trunks and branches during the colder months. It creates tunnels as it feeds and then chews its way out as an adult in the warmer months.
Trees that have been infested will not survive.
What to look for when checking for Asian longhorned beetles
Asian longhorned beetles have not yet been discovered in Michigan, but environmental officials want residents to keep an eye out.
If infestations are discovered early, it can prevent widespread damage to forests, urban landscapes and maple syrup production.
Look for the following signs when you’re outside:
- Round exit holes, about the diameter of a pencil, found in tree trunks and branches.
- Shallow oval or round scars in the bark, where the adult beetle chewed an egg site.
- Material that looks like wood shavings lying on the ground around the tree or in the branches.
- Dead branches or limbs falling from an otherwise healthy-looking tree.
Adult Asian longhorned beetles are large and range from 3/4 to 1 1/2 inches in length. That doesn’t include their long antennae. They are shiny black and have random white blotches, or spots.
Their antennae have alternating black and white segments. They have six legs that can be black or partly blue, with blue coloration -- sometimes extending to their feet.
Native bugs that look similar
There are a few beetles and bugs that are native to Michigan but can be mistaken for the Asian longhorned beetle:
- The white-spotted pine sawyer has a distinctive white spot below the base of its head – between its wings – and is brownish in color.
- The cottonwood borer is about the same size as the Asian longhorned beetle and is also black and white, but it has a pattern of single, broad black stripes down each wing, and its antennae are all dark.
- The northeastern pine sawyer reaches up to 2 inches in length, has very long antennae and is gray in color.
- The eastern eyed click beetle has distinctive eye circles on the back of its head. It rolls over when threatened, then clicks and makes a flipping movement to get back on its feet.
What to do if you find an Asian longhorned beetle
If you find an Asian longhorned beetle or a tree that appears to have been damaged by it, you should report it.
You can report it by calling the USDA ALB hotline at 1-866-702-9938 or submitting an online report through the USDA’s Asian longhorned beetle website. Try to get a picture of the beetle or tree damage. If you can, capture the beetle in a durable container and freeze it. Freezing the beetle helps preserve the insect for identification.