Invasive Species Spotlight--Asian
Longhorned Beetle
The Asian longhorned beetle is an exotic pest that threatens
a number of hardwood trees
in North America. It is
believed that this insect arrived in North America
in wooden
packing material from China.
This woodboring beetle goes through four life stages: egg,
larva, pupa, and adult. The
eggs are laid by adult beetles on the bark of living trees.
A single female can lay up to
90 a year with each egg being placed in its own site. Eggs
are encased in a brownish
protective secretion about ¼ inch in diameter. The larva
emerges from this egg site in
about 10 to 15 days and begins burrowing into the tree's
bark. They begin by feeding on
the sapwood around the tree but later feed on the heartwood
and overwinter in there. In
the springtime they continue feeding until they begin their
pupal stage. This may last
over a week as it begins transformation into its adult form.
Adults are generally present from June through October. They
can range in size from 1 to
1 ½ inches long. They are black with white specks on its
elytra (wing covers) and have
long white and black banded antennae. Females tend to be a
bit large than the males.
From Left to Right: Cottonwood Borer (a similar looking
beetle native to the US),
Female
ALB, Male ALB.
The greatest damage to trees is caused by the larva as they
tunnel through the living
tissues of the phloem and xylem. Ultimately the tree loses
its ability to transport water
and nutrients to its canopy and roots and dies. Because the
ALB can be quite large it can
also weaken the structural integrity of a tree.
Larva (Picture taken by: ALB Steven Katovich, USDA Forest
Service)
Visual symptoms of an infested tree can include the
accumulation of frass on tree branch
collars below holes cause by exiting beetles. Exit holes can
be quite large and distinct
from other longhorned beetles; up to ½ inch in diameter and
almost perfectly circular.
Adult beetles can also be found chewing on the veins of
leaves leaving the other leaf
tissues intact. Egg sites can also be an important visual
clue to their presence.
Frass and sawdust left below holes.
Asian Longhorned Beetles have a wide range of preferred host
trees. Most studies show that they prefer maple trees of any species. Its other top
choices include: birch, horse
chestnut, poplar, willow, elm, ash, hackberry, sycamore,
mountain ash, and London
plane
tree as well as many others.
Damaged heartwood and adult beetle
The Asian longhorned beetle was first identified in New York City in 1996.
Two years later
it was detected in a Chicago
neighborhood and in 2002 in New
Jersey. When entomologists and resource managers from numerous organizations first learned
of the destructive potential of the insect they quickly made plans to try and eradicate it.
The first steps were to survey for damage and then to establish quarantine zones. Surveys
were done using aerial lifts and then to establish quarantine zones. Surveys were done using
aerial lifts and then to establish quarantine zones. Surveys were done using
aerial lifts.
Four months after the beetle was declared eradicated from
the Chicago-land area it was
found in Deerfield in
August 2008. However, extensive survey efforts have not found any
infestation or other signs of this invasive pest. If you
suspect the Asian Longhorned
Beetle anywhere in Illinois
please contact: The Illinois Department of Agriculture at
1-800-641-3934
.
Photos courtesy of www.bugwood.org.--Kelly Estes
Author:
Kelly Estes