Beetle emergence holes, the size of the diameter of a pencil lead, and/or sawdust on the bark, indicate burrowing beetles. The beetles are 3.5 mm in size.
Actual size of beetle
 European elm bark beetle |
 Native elm bark beetle |
The characteristic pattern of the breeding galleries on the surface of the wood under the bark can also be used to identify these two beetles.
 Actual wood sample of beetle galleries |
 Upper beetle gallery - with the grain - European Lower beetle gallery - across the grain - Native Upper beetle - European Lower beetle - Native |