Asian Longhorned Beetles came to North America in wooden packing crates from China. Although, to date, they are only known to be attacking trees in southeastern New York State and the Chicago, Illinois area, they have been found in warehouses all over the United States and in Canada.
The adult beetles are big and dramatic looking. They are about 7cm long with antennae up to 2.5 times their body length (hence the name 'longhorn'). They are black with white flecks. The legs and antennae are banded with a slight bluish tint. They may be seen at any time from early spring to late autumn feeding on twig bark.
The female Asian Longhorned Beetle lays 30 to 75 eggs in a shallow cone-shaped excavation, which she has chewed into mature bark. She then covers the eggs with a sticky secretion. The larvae feed in tunnels near the surface, until they are ready to pupate in the heartwood. The resulting matrix of tunnels, each perhaps 1.5cm in diameter, may weaken a tree to the point where it falls over, or parts of it fall off. Either way the vascular* system will become so damaged that the tree may die*.
Asian Longhorned Beetles are giving urban forestry people nightmares, because the species are most fond of trees found in cities: namely, Norway Maples (and their many popular cultivars) and Chestnuts. They are also known to attack Black Locusts, Elms, and Birch. In fact, because they are new arrivals, they could develop a taste for practically anything, and they have no natural enemies. So far, the only cost-effective control measure is to cut down infested trees and destroy them, in the hope of also destroying the beetles.
On a brighter note, Asian Longhorned Beetles are known to be reluctant travellers. They can fly; but, due to their size, prefer not to. So infestations tend to be limited to relatively small areas.
Adult Asian Longhorned Beetles are quite easy to spot. Their presence, especially the presence of their young, can also be surmised from such evidence as mounds of sawdust on the branches of trees and holes resembling bullet wounds in the bark. The egg patches, resembling dark smears on the bark, may also be apparent.
Asian Longhorned Beetles could be to this generation of foresters what Dutch Elm Disease was to the last... a nightmare! If you see an Asian Longhorn Beetle, or suspect the beetles are present in trees, do notify the authorities. In Illinois, for example, there is a hotline to report sightings. There are bound to be other reporting facilities in other areas.