Signs and Damage Pictures of ALB and CLB

Asian longhorned beetle (ALB) and citrus longhorned beetle (CLB) share similar host preferences: maple (Acer sp.), birch (Betula sp.), elm (Ulmus sp.), willow (Salix sp.), and horsechestnut (Aesculus sp.). In addition, CLB will readily attack apple (Malus sp.), oak (Quercus sp.), beech (Fagus sp.), citrus (Citrus sp.), and others.
Look for these signs year-round on deciduous host trees:

(click on images to enlarge)

The Beetles:

Adult beetles of both species are glossy black with distinct white splotches on the wing covers. They are large (1 - 1-1/2 inches long) and have antennae at least the length of the body. Antennae are starkly banded black and white.
and CLB can be seen July to October.

Asian longhorned beetle adult female

L-R: Citrus longhorned beetle (exotic), Asian longhorned beetle (exotic), Whitespotted Sawyer (native - do not report)
(Photo credits (L-R): Pest and Diseases Image Library; Steven Valley, Oregon Department of Agriculture; Michael Bohne, USFS)

Oviposition Sites:

Egg-laying sites:
ALB - oval pockmarks in the bark where an adult female has chewed a depression to lay an egg.
more images
CLB - T-shaped scars on the bark at the base of the trunk that are approx. 1/8 to 3/16 in long and approx. 1/16 in wide.

Egg-laying sites and exit holes of ALB (Photo by Dennis Haugen, USDA Forest Service)

T-shaped oviposition site of CLB

Egg-laying sites of CLB (Image in Haack et al., 2010)

Exit Holes:

ALB - round holes ~3/8 to 1/2 in diameter on the trunk or branches. A pencil can be inserted at least an inch into an ALB exit hole.
more images
CLB - round holes ~3/8 in diameter at the base of the trunk or exposed roots.

ALB exit hole with pencil

ALB Exit hole (Photo by Rutgers University)

ALB exit holes

CLB Exit holes (Photo by EPPO)

Tunnels and Galleries:

Larval feeding tunnels meander towards the heartwood, where it will then pupate to complete development.

Look for these signs in split and cut wood.

ALB tunnels and pupal chambers

ALB larval tunneling and pupal chambers (Photo by Patricia Douglass, USDA APHIS PPQ)

ALB pupal chambers

CLB larval tunneling - found at the base of the tree and exposed roots (Image in Haack et al., 2010)


Frass is sawdust-like material which the beetle larvae push out as it feeds in the tree. This may be found in oviposition sites, exit holes, branch junctions, or on the ground.


Frass coming out of ALB egg-laying site (Photo by Kenneth R.Law, USDA APHIS PPQ)

ALB and frass

ALB and frass on the ground (Photo by Michael Bohne, USDA Forest Service)