Forest Health Protection-Asian Longhorned Beetle:
The First Line of Defense
Asian Longhorned Beetle:
The First Line of Defense
- You may not know it, but you are part of the main line of
defense against a serious threat to one of our country's most valuable
our hardwood trees.
- Many of our nation's most common hardwoods and shade trees
are threatened by a pest against which they have no natural defense, a pest
that could change forever the quality of life in our country. That pest is the
Asian longhorned beetle, or "ALB" for short.
- The purpose of this program is to show you how to recognize
the Asian longhorned beetle, identify signs of attack, and report suspicious
finds. If we are to have any chance of stopping the ALB, people like you will
have to help us discover new infestations so they can be contained and
- The Asian longhorned beetle is a native of China and other
areas of eastern Asia. In China it causes widespread damage and death in hybrid
poplar plantations. These plantations are salvaged and the low-quality,
infested wood is sometimes used to make crates and pallets.
- The beetles are transported to this continent in these
infested, wooden packing materials. Once here, they can escape and infest trees
in surrounding areas.
- Prior to 1996, there were no known infestations of ALB in
North America. The first infestation in the U.S. was discovered in New York
City in 1996. This was followed by the report of a second infestation in
Chicago in 1998. Within months of the initial discoveries, Asian longhorned
beetles were found in several different urban and suburban settings in both
cities. Millions of dollars have been spent trying to rid these areas of ALB
and thousands of high-value shade trees already have been lost. ALB also has
been found in dozens of port and warehouse locations nationwide. Such
accidental introductions have the potential to develop into new infestations of
- The ALB's favorite host trees are maples, but it will also
attack elm, horsechestnut, willows, and poplars. The ALB does not attack
conifers or evergreens. Adult females chew out small pits in the bark and lay
their eggs in them. The eggs hatch and the young grubs tunnel into the cambium,
causing branch die-back. The grubs tunnel deeper into the tree as they grow.
This tunneling eventually kills the tree by cutting off the flow of water and
nutrients. Tree death is caused by repeated attacks over several years.
- Because the Asian longhorned beetle spends so much of its
life cycle deep inside the tree, traditional insect control methods like
insecticides are proving extremely difficult to develop.At this time, removing
the infested trees and then burning or chipping them is the only viable option
for eradication of the ALB. This is a costly, time-consuming solution which may
have severe economic and aesthetic consequences.
- There are three basic steps to the ALB eradication
strategy: eradicate (or destroy) the known infestations; break the pathway of
infested wood; and find any undetected infestations.
- Known infestations are being intensively surveyed and
eradicated.Surveying is done with tree climbers, people in bucket trucks, and
ground crews with binoculars. Once the infested trees are removed, Federal,
state, and local agencies are cooperating to help the affected areas recover.
Quarantines in the known infestations place restrictions on the movement of
certain types of wood from these areas to prevent ALB from being moved
accidentally to uninfested areas.
- The USDA has taken steps to help fight ALB by breaking the
pathway of infested wood from China. Since 1998, all solid-wood packing
material from China must be treated before entering the United States.
- Perhaps the most important part of ALB eradication is the
early detection of infestations. This is where your assistance is so vital.Why
do we need your help? There are so many places that the ALB may be present, and
looking for attacked trees is so difficult and time-consuming that the
regulatory agencies cannot do the job alone.If we can inform citizens,
especially people who work regularly with trees, we can greatly improve our
odds of finding infestations quickly enough to eradicate them. Finding new
infestations as soon as possible may make the difference between getting rid of
ALB completely and having to live with this serious tree pest on a permanent
- In order for you to help with early detection of ALB
infestations, it is necessary to know a little bit about the beetle.
- Like many insects, the beetle has 4 life stages: egg, grub,
pupa, and adult. The most destructive life stage is the grub, but these are not
likely to be seen because they burrow into the tree.
- The best way to spot an infestation is by observing the
actual adult beetle. The adult beetles are large: ¾ to 1 ¼ inches
long.* They are jet-black with distinctive white spots on the back.
- They have antennae which are black-and-white banded and
very long: 1½ to 2 times longer than the beetle's body.In addition, the
feet and legs often have a bluish tinge.
- The most common time of the year to spot the adult beetles
is June through October.
- There are a few native beetles that resemble the Asian
longhorned beetle. Beetles such as the white-spotted pine sawyer and the
cottonwood borer may be easily confused with ALB. Although they have some
charactersitics that are different from ALB, many people may not be able to
tell them apart with certainty. It is better to be safe than sorry - if you see
any beetle that may be an Asian longhorned beetle, be sure to follow the steps
we will give you shortly to report your find.
- Even if you don't observe the actual adult ALB, there are
signs of damage that can warn you that an ALB infestation may be taking place.
The most definitive sign of damage is the distinct exit hole. After pupating,
the mature adult chews its way out of the tree to disperse and mate. This
leaves a perfectly-round exit hole on the outside of the tree. This hole is 3/8
to ½ inch in diameter** and looks as clean as a hole made with a
- There are other, less-definitive signs that an ALB
infestation may be happening. Egg sites are oval to round pits in the tree bark
chewed out by the adult female for egg placement. Often, sap is seen flowing
from these egg sites.
- As the ALB grubs bore into a tree, they create sawdust that
is pushed out of their tunnels. This coarse sawdust often builds up where
branches come together, where branches meet the main stem, and around the bases
of the attacked trees. Sap or sawdust alone are not signs that a tree is
infested with ALB, as other insects or activities may cause these signs to
occur. However, if you see sap or sawdust on a maple tree or one of the other
major host trees, these may be warning signs that ALB is present and you should
look carefully at the rest of the tree for beetles, exit holes, or egg
- As important as knowing what to look for is where to look.
Maples are ALB's favorite host trees. If you have maples in your area, this is
the most likely place for an infestation to start. Accordingly, you should be
most alert for ALB in and around maple trees.
- Other trees that attract the ALB are elm, horsechestnut,
willows, and poplars. ALB will attack additional tree species as well, although
not commonly. A complete list of host trees in North America has yet to be
established. Look for ALB on live and dying hardwood trees, but not on
completely dead trees because ALB does not attack these.
- One reason that infested trees are difficult to spot is
because the ALB usually attacks smaller branches in the tree crown first. Only
later, when the beetles are attacking the larger branches and main stem, can
signs of attack be seen from ground level. The most thorough way of inspecting
a tree is to look at all parts of it (with the exception of the branch
- What should you do if you see a possible ALB infestation?
If you see a beetle that might be an ALB, try to capture it in a container and
place the container in the freezer to kill and preserve the specimen. Be sure
to write down exactly where and when you found the beetle. Noting the exact
location is critical so follow-up surveys can be done. In some cases it may be
necessary to mark the tree in question with paint or flagging.
- If you see exit holes, egg sites, or sawdust which may have
been made by ALB, once again write down detailed location information for the
tree and also note the specific location in the tree where you saw the
- Any information you have on possible ALB attacks should be
passed on to your supervisor, company owner, or one of the following agencies.
- County cooperative extension, state department of
agriculture, state forestry department or state department of natural
resources, USDA Animal and Plant Health Inspection Service, or USDA Forest
Service.A list of specific contact phone numbers for your area has been
provided along with this video.
- You are truly one of the first lines of defense against
this serious pest. With every passing day that an Asian longhorned beetle
infestation goes undetected, our chances of eradicating it from the U.S.
decrease. You might ask, "exactly what is at risk from the Asian longhorned
beetle if we don't eradicate it?" Roughly 30% of urban and suburban trees in
the U.S. are maples, ALB's main target. The various forest-related industries
at direct or indirect risk from ALB are valued at $41 billion. In the eastern
U.S. alone, 4 million jobs depend on forests that the Asian longhorned beetle
may damage. Finally, there are immeasurable aesthetic and sentimental values
associated with many trees the ALB may kill. You can see that the ALB could
become a serious problem nationwide if we are not alert. Please make it a habit
to look for and notice the things we've discussed.
- The presence of the
large, striking adult beetle with its white-spotted body and long, banded
- The perfectly-round
and smooth exit holes on the outside of trees. The exit holes are 3/8 to
½ inch in diameter**.
- The ALB is a serious pest, but with your help on the main
line of defense, we can stop it before irreparable harm is done to our nation's
valuable hardwood and shade trees.