A recent immigrant to the United States, the Asian Longhorned Beetle made its presence known quickly. Accidental introductions, probably in wooden packing crates from China, led to infestations in New York and Chicago in the 1990's. Thousands of trees were chipped and burned to prevent its spread. More recently, Anoplophora glabripennis appeared in New Jersey and Toronto, Canada. What makes this beetle so dangerous to our trees? All four stages of the life cycle damage the host trees.
The Asian Longhorned Beetle belongs to the family of wood boring beetles, Cerambycidae. Adult beetles measure 1-1½ inches in length. Their shiny black bodies have white spots or markings, and the long antennae have alternating black and white stripes. The Asian Longhorned Beetle may be mistaken for two species native to the U.S., the cottonwood borer and the whitespotted sawyer.
All other stages of the life cycle occur within the host tree, so it's not likely you will see them. The female chews away a small amount of bark and lays white, oval eggs singly within the tree. Larvae, which are also white and resemble small grubs, chew their way through the vascular tissue of the tree and move into the wood. Pupation happens within the tunnels the larvae create in the wood. The newly emerged adult chews its way out of the tree.
Usually, identification of this pest is made by observing damage to the host trees, and then finding an adult beetle to confirm the suspected infestation. When the female oviposits, it causes the sap to weep. When a tree has multiple wounds with dripping sap, wood borers may be suspected. As the adults chew their way out of the tree, they push large amounts of sawdust from their exit holes. This accumulated sawdust, usually around the base of the tree or piled in the crotch of branches, is another sign of the Asian Longhorned Beetle. The adult beetle emerges from an oval exit hole about the size of a pencil eraser.
Asian Longhorned Beetles feed on wood of many common hardwood species: birches, common horsechestnuts, elms, hackberries, london planes, maples, mountain ashes, poplars, aspens, and willows. They show a particular preference for maples. Larvae feed on the phloem tissue and wood; adults feed on bark during their mating and egg-laying period.
Asian Longhorned Beetles undergo complete metamorphosis with four stages: egg, larva, pupa, and adult.
Egg - Eggs are laid singly within the host tree's bark, and hatch in 1-2 weeks.
Larvae - Newly hatched larvae tunnel into the vascular tissue of the tree. As they mature, larvae migrate into the wood, causing extensive damage. Larvae may reach 5 cm in length when fully grown, feeding for at least 3 months.
Pupa - At maturity, the larvae move near the surface of the tree (under the bark) to pupate. Adults emerge in about 18 days.
Adult - The adult beetles actively mate and lay eggs throughout the summer and fall.
Special Adaptations and Defenses:
Asian Longhorned Beetle larvae and adults chew wood with large mandibles. Adults, especially males, display long antennae used to sense the sex pheremones of potential mates.
Areas where host trees are available, particularly where maples, elms, and ash are in abundance. In the U.S. and Canada, known Asian Longhorned Beetle infestations have occurred in urban areas.
The Asian Longhorned Beetle's native range includes China and Korea. Accidental introductions expanded the range to include the United States, Canada, and Austria, hopefully temporarily. The introduced populations are believed to be under control.
Other Common Names:
Starry Sky Beetle, Asian Cerambycid Beetle