Asian longhorned beetle—Anoplophora glabripennis
This longhorned beetle, or roundheaded wood borer (Cerambycidae), aggressively attacks apparently healthy broadleaf trees in the eastern United States. This pest is not established in California as of 2017.
The boring larvae cause liquid ooze and sawdustlike frass (excrement) on bark and dying limbs. The initially low populations of borers in a tree can easily be overlooked. After larvae pupate, each emerging adult leaves a relatively large, smooth-edged hole about 1/2 inch in diameter in bark.
Adults are shiny and mostly black. Each wing cover (elytron) has about 20 white blotches. The antennae have 11 segments; each segment is bluish black with a whitish base. The antennae of the males are more than twice the body length, hence the name longhorned. The antennae of females is about one and one-half the body length. Mature larvae, pupae, and the body of adults are about 3/4 to 1-1/4 inches long.
The introduced Asian longhorned beetle can be distinguished from several native species by differences in their markings. For example, the native banded alder borer thorax is white with a single, large, black spot that is one-half or more of the width of the thorax. The thorax of Asian longhorned beetles is entirely shiny black.
Life cycle
Asian longhorned beetles develop though four life stages—egg, larva, pupa and adult. The adult female can lay up to 90 eggs, one egg each at the bottom of irregular-shaped craters she chews in bark. In a lightly infested tree, these dime-sized, egg-laying pits are more common near to the top of the tree and on larger branches. In a tree that is heavily infested, egg-laying craters can be found on bark throughout the tree.
After hatching, the larva chews into the tree and feeds initially in cambium and sapwood, and later in heartwood. Larvae develop through five, increasingly larger instars (growth stages) before pupating in a chamber the mature larva chews in sapwood.
Adults emerge and mate, and the females lay eggs. Females feed on leaf midribs, leaf petioles, and twig bark. About 2 years are required to complete one generation in the eastern Untied States.
Damage
Asian longhorned beetle damages the appearance and health of various hardwood trees. Infested trees drop dead branches, and eventually die. Quarantines intended to stop the beetle's spread require the prompt removal of infested trees. Hundreds of thousands of trees have been removed in the eastern United States in an ongoing effort to prevent this pest from spreading.
Solutions
Because Asian longhorned beetle aggressively attacks apparently healthy broadleaf trees, avoiding its introduction, establishment, and spread are the primary management methods. Submit any suspected Asian longhorned beetles found in California to the county agricultural commissioner.
To avoid spreading wood-boring pests, do not move firewood or logs to other counties. Purchase firewood near where you will burn it, and leave any unused wood on site rather than moving it or bringing it home.
To avoid damage from most wood borers, plant trees that are well adapted to the site conditions, provide proper cultural care, and protect trees from injuries. Prune off dead limbs during the season when adult borers are not active. Promptly remove dead or dying trees. Do not store freshly cut wood near trees; debark or solarize logs beneath clear plastic in the sun to prevent beetles from emerging from cut wood and attacking nearby hosts.
See the U.S. Forest Service website for more information on Asian longhorned beetle. |
