The Michigan DNR wants people to start checking trees for adult Asian longhorn beetles.

This is because August is when the beetle is most likely to be seen and the damage it causes to trees is most likely.

By keeping an eye out for the beetle and the damage it leaves behind, you can protect trees and fight an invasive species. Michigan authorities are asking citizens to take 10 minutes this month to check the trees around their homes.

Although the beetle has not yet been detected in Michigan, officials say it is “critical that we keep an eye out for it.” Detecting early signs of an infestation can prevent widespread damage to the state’s forests, urban landscapes and maple syrup production.

What is the Asian longhorn beetle (ALB)?

It is an invasive wood-boring beetle that attacks 12 species of deciduous trees, including maples, elms, horse chestnuts, birches and willows. It has no predators or diseases to keep its population in check.

In the larval stage, the snake feeds on tree trunks and branches during the colder months. As it feeds, it digs tunnels and then gnaws its way out as an adult in the warmer months.

Trees that are infected will not survive.

What to look for when searching for Asian longhorn beetles

Asian longhorned beetles have not yet been detected in Michigan, but environmental officials are urging the public to keep their eyes open.

Early detection of infestations can prevent widespread damage to forests, urban landscapes and maple syrup production.

Watch for the following signs outdoors:

• Round exit holes with about the diameter of a pencil can be found in tree trunks and branches.

• Flat oval or round scars in the bark where the adult beetle has chewed the site of an egg laying.

• Wood chip-like material found on the ground around the tree or in the branches.

• Dead branches or twigs falling from an otherwise healthy-looking tree.

Adult Asian longhorn beetles are large, ranging from 19 to 4 cm in length, not including their long antennae. They are shiny black with occasional white spots or dots.

Their antennae have alternating black and white segments. They have six legs, which may be black or partially blue, with blue coloring sometimes extending to the feet.

Similar looking native beetles

There are some beetles and bugs that are native to Michigan but can be confused with the Asian longhorn beetle:

• The White-spotted Pine Warbler has a characteristic white spot below the base of the head – between the wings – and is brownish in colour.
• The poplar borer is about the same size as the Asian longhorn beetle and is also black and white, but has a pattern of individual broad black stripes on each wing and its antennae are completely dark.
• The Eastern eyed click beetle has distinctive eye rings on the back of its head. When threatened, it rolls over, clicks, and then performs a somersault motion to get back on its feet.

What to do if you find an Asian longhorn beetle

If you find an Asian longhorn 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 by Online report on the USDA website on the Asian longhorned beetle. Try to take a picture of the beetle or the tree damage. If possible, capture the beetle in a durable container and freeze it. Freezing the beetle will help preserve the insect for identification.