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Where are the ALB now?

With the cold now upon us, adult Asian longhorned beetle (ALB) have since died off, but their life cycle continues unseen.  At this point, the larvae have long since hatched and burrowed into any tree that their eggs were laid on, and that is where the real damage from this invasive insect is occurring. From the site where the egg was deposited, a newly-hatched larva chews its way into the tree, where it creates hollow galleries. The larva initially starts in the cambium layer, which is the living layer of wood just under the bark, responsible for the transportation of water and nutrients. It then keeps going into the heartwood, the interior of the tree. The galleries it creates lead to structural damage and ultimately the death of the tree. Trees may respond with compartmentalization, a process where trees grow new thick tissue to partition off damage and resume the flow of nutrients through the cambium layer. However, in trees that sustain heavy damage from ALB, this process is insufficient and the tree eventually dies.

ALB larva in gallery

Deep inside the host trees, ALB larvae and pupae can easily survive the snow and cold winter months ahead. They are so deep inside the tree that they are also protected from predators like woodpeckers who might want to make a meal out of a defenseless grub.

ALB pupa in gallery with frass

That means that at this time of year, while you will not see the beetle itself, the larva are still there inside the tree, chewing away. Fortunately, you can still spot external signs of damage on host trees, such as eggs sites or exit holes. If you see any of these telltale signs of damage, report them by submitting descriptions and pictures of damage to our website. You can also refer to and print out guides showing the host trees of ALB here.

Exit hole from adult beetle, with egg sites, on tree

Egg site on surface of host tree

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