Infestation and Detection
Infestation
ALBs most commonly spread by natural means; under its own power an ALB can fly distances greater than 400 yards. Migration may also depend on the abundance of suitable host materials (e.g., hardwood trees).
After mating, adult females chew depressions into the bark of various hardwood tree species in which they lay (oviposit) their eggs.
Once the eggs hatch, small white larvae bore their way through the bark into the tree, feeding on the sensitive vascular layer beneath. The larvae continue to feed deeper into the tree's heartwood, forming tunnels, or galleries, in the trunk and branches. This damage weakens the integrity of the tree and will eventually kill it if the infestation is severe enough.
 After maturing, the ALBs leave behind deep, perfectly round exit holes somewhat larger than the diameter of a pencil. Tree exit holes may ooze sap, and deposits of frass (insect waste and sawdust) may collect at tree trunk and tree limb bases. Egg deposit sites can be found by looking for oval-shaped, dimpled impressions in tree bark.
Unseasonable yellowing or drooping of leaves when the weather has not been especially dry is also a sign that the ALB is present. Leaf symptoms show up when the immature insects, growing inside the tree, have bored through tissue that carries water (xylem) from tree roots and nutrients (phloem) from the leafy canopy above. Once the pest has sufficiently disrupted those pathways, the infested tree will die.
Detection
ALB inspectors utilize many methods and resources to conduct tree surveys.
- Aerial tree inspections are performed by trained professionals using bucket trucks to peer into trees from above.
- FS and state smokejumpers (forest firefighters) climb trees in otherwise inaccessible areas to scrupulously search for signs of an infestation.
- Many interest groups and organizations voluntarily assist inspectors by searching trees from the ground.
- Anyone with a keen eye and set of binoculars can contribute to this effort.
Detecting and eradicating the ALB is a cooperative effort. APHIS works closely with many agencies and resources to inspect for and detect the ALB, including:
- Forest Service (FS) and Agricultural Marketing Service
- New York Department of Agriculture and Markets
- New York State Department of Environmental Conservation
- New York City Department of Parks and Recreation
- Illinois Department of Agriculture
- Chicago Department of Streets and Sanitation's Bureau of Forestry
- New Jersey Department of Agriculture
- New Jersey Department of Environmental Protection
- Privately contracted tree-service professionals
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