Anoplophora glabripennis
The invasive Asian longhorned beetle (ALB), Anoplophora glabripennis, has been discovered attacking trees in the United States. The ALB arrived in the United States within hardwoods cut into crates and pallets and used to import goods from Asian countries. There are currently known infestations being eradicated in New York, Illinois, and New Jersey. Damage from these infestations has resulted in the removal of more than 30,000 trees and costs in excess of $269 million since the discovery of the infestations in 1996. The ALB was recently confirmed in Worcester, Massachusetts. The proximity to Connecticut puts our forests at risk. The ALB is a serious threat to U.S. trees. The ALB has the potential to wreak havoc nationwide, affecting such industries as lumber, maple syrup, nursery, and tourism.
Host Plants
This beetle is a serious pest in China where it kills hardwood trees in roadside plantings, shelterbelts, and plantations. In the United States the beetle prefers maple species (Acer spp.), including boxelder, Norway, red, silver, and sugar maples. Other known hosts are alders, birches, elms, horse chestnut, poplars, and willows. A complete list of host trees in the U.S. has not been determined. In addition to the states where eradication measures have been implemented, the ALB has been reported in the past decade in warehouses in California, Alabama, Florida, Indiana, Michigan, North Carolina, Ohio, Pennsylvania, South Carolina, Texas, Washington, and Wisconsin.
Life History
The ALB has one generation per year. Adult beetles are usually present from July to October, but can be found later in the fall if temperatures are warm. Adults usually stay on the trees from which they emerged or they may disperse short distances to a new host to feed and reproduce. The adult beetle is about 1 to 1.5 inches long. Shiny black with white spots, it has exceptionally long antennae that are banded with black and white. The elongated feet are black with a whitish-blue upper surface. Although its size and large mandibles cause it to appear threatening, the beetle is harmless to humans and pets. Each female can lay up to 160 eggs. Single eggs are laid in chewed out oval to round pits in the bark. The eggs hatch in 10-15 days and the white, worm-like larvae tunnel under the bark and into the wood where they eventually pupate. The adults emerge from pupation sites by boring a tunnel in the wood and creating a 3/8” or larger round exit hole on the trunk or branches.
Signs of Infestation
Signs of infestation by the ALB include the presence of adult beetles, egg deposit sites, piles of frass at the base of infested trees and in branch crotches, sap leaking from wounds in the trees, and exit holes (see images below) created by the emerging adults. Leaf symptoms show up when the immature insects, growing inside the tree, have bored through tissues that carry water from tree roots and nutrients from the leafy canopy above. This may include unseasonable yellowing and drooping of leaves when the weather has not been especially dry. Once the infestation is sufficiently advanced, the infested branch or the entire tree will die.
