Spot It

The adult ALB (Asian Longhorned Beetle) is a distinctive-looking insect with the following unique characteristics:

  • 1 inch to 1 ½ inches in length
  • Long antennae banded with black and white
    (longer than the insect’s body)
  • Shiny, jet black body with distinctive white spots
  • Six legs
  • May have blue feet


While the ALB may appear threatening, it is harmless to humans and pets.

Know The Signs

exit holes

In the summer, the adult beetles chew their way out, leaving dime-sized, 1/4 inch or greater, perfectly round exit holes.

Oval Impressions

The adult female chews 35-90 oval depressions, called oviposition sites, into the bark of the host tree. She lays a single egg beneath the bark at each site.

ALB produces frass

As the beetle tunnels, it often pushes sawdust-like material, called frass, out onto the ground or tree branches.

Beetle hatching into white caterpillar

Eggs hatch into white worm-like larvae that tunnel deeper into the tree, where they feed and continue to develop over the winter months.

multiple exit holes

Infested tree with exit holes and egg sites.

Asian Longhorned Beetle: How did it get here?

Asian Longhorned Beetle: Live

Asian Longhorned Beetle: The Signs

Asian Longhorned Beetle: Spot and Report It

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Frass thumbnail
Larvae thumbnail
Multiple Exit Holes thumbnail
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Trees At Risk

Click on a leaf in the left bar for more information.

  • Ash
  • Birch
  • Elm
  • Goldenrain tree
  • Horsechestnut
  • Katsura
  • London Planetree
  • Maple
  • Mimosa
  • Mountainash
  • Poplar
  • Willow
When You Can Spot It

Adult beetles are most active during the summer and early fall. Throughout the summer, they can be seen on tree branches, walls, outdoor furniture, cars and sidewalks. During the winter months, the beetle’s larvae tunnel deep into and feed on the trees they infest.

Click on this life cycle
image to enlarge.

ALB Look-alikes

There are ALB look-alikes, but the most common is the Whitespotted sawyer, which is often mistaken for the ALB. Here are the telltale differences:

  • The Whitespotted sawyer has one white dot between the top of its wings. ALB does not have this dot.
  • The Whitespotted sawyer’s wings are rough and bronzish-black as opposed to the ALB’s shiny smooth black wings.

Click on this comparison
image to enlarge.