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Action

EAB News

July 24, 2009
NYS institutes emerald ash borer quarantine
of Cattaraugus and Chautauqua counties. More...

July 1, 2009
US Senator Chuck Schumer unveils 3-point plan
to fight spread of EAB.

July 9, 2009
US Senator Chuck Schumer announces USDA APHIS-PPQ
funding to NYS doubled for fight against
EAB.

Home > Insects >
Emerald ash borer

Emerald Ash
Borer
(Agrilus planipennis)

Biology &
Identification

Hosts

Signs of
Infestation

Impacts

Management
& Control

EAB
Resources Page

Agrilus
planipennis

Introduction

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera:
Buprestidae), commonly referred to as “EAB”, is an invasive wood-boring
beetle. Its native range is eastern Russia, northern China, Mongolia,
Korea, Japan and Taiwan. The beetle’s first North American populations
were confirmed in the summer of 2002 in southeast Michigan and in Windsor,
Ontario. Judging by the size of the infestations and the stage of damage
to the infested trees, the beetle was likely introduced to the area
several years prior to its discovery. It is

believed that the beetle was
introduced into

Multi-state distribution August 17, 2010

North America in ash wood
used for shipping pallets and wooden packing materials in cargo ships or
shipping containers.

NYS distribution
Summer 2010

Since its introduction into North America, EAB has spread into 13 states
(Illinois, Indiana, Kentucky, Maryland, Michigan, Minnesota, Missouri, New
York, Ohio, Pennsylvania, Virginia, West Virginia and Wisconsin) and two
Canadian provinces (Ontario and Quebec). EAB was first confirmed in New
York in June 2009 near Randolph, in western Cattaraugus County. [Click to read NYS DEC /
NYS DAM press release]

Emerald ash borers
are not particularly strong fliers, with adults typically flying less than
½ mile from their emergence tree. The natural dispersal of EAB in North
America is assumed to be 5 miles (8 kilometers) or less per year. The
rapid spread of the

NYS EAB
distribution and threat levels

beetle since its North American introduction is most likely
due to the unintentional transport of infested ash nursery stock,
firewood, unprocessed ash logs, and other ash products. In an effort to
slow the continued spread of EAB, both the Federal and State governments
have instituted various quarantines of infested area to regulate the
continued transport of ash products. [Click to
read about the NYS quarantine]

USDA
APHIS (the United States Department of Agriculture Animal and Plant Health
Inspection Service), in cooperation with state natural resources agencies
and others, has instituted an EAB survey to identify the leading edge of
known infestations and to locate new or outlying populations. Traps are
generally placed in a 1 1/2 miles by 1 1/2 mile grid where ash is found
within a 100-mile band of known EAB infestations. The survey detection
tool is a 24 inch (60 cm) corrugated purple plastic prism-shaped trap that
is coated with non-toxic glue on all three sides and is baited with an oil
lure to attract the adult beetles. [Click here to find
out more about the 2009 EAB Survey]

Biology and
Identification

Emerald ash
borers are members of a group of insects called metallic wood-boring
beetles (Buprestidae). Adult

EAB
trap

EAB have bronze, golden, or reddish-green bodies, with dark
metallic emerald green wing covers. The dorsal side of the abdomen, which
can be seen when the wings

are spread, is a metallic
purplish red. Adult beetles average 3/8 inch to 3/4 inch (10 mm to 20 mm) long
and 1/6 inch (4 mm) wide (males are slightly smaller than females). EAB
generally have a 1-year life cycle, emerging from beneath the bark of ash trees
from late-May through early-June with peak activity between mid-June and
early-July, tapering off by the middle of August. Adult beetles are most active
during the day and favor sunny, warm weather, sheltering in bark crevices or
under foliage when it is rainy, windy or cooler. The life span of adult EAB is
about 3 weeks.

EAB adults feed along the margins of leaves, leaving
small, irregular shaped edges. Newly emerged adults must feed for at least
several days before mating; mated females feed for an additional 1 to 2 weeks
before laying eggs (females can mate multiple times; males do not). An “average”
female may lay between 60 and 90 eggs during her lifespan, placing the
reddish-brown eggs singly in bark crevices or under bark flaps on the trunk or
branches (some long-lived females may lay more than 200 eggs).

EAB
larvae

Eggs hatch in 7 to 10 days. The
slightly flattened, white to cream-colored larvae have 10 abdominal
segments with a pair of brown, pincher-like appendages on the last
segment. EAB larvae go through five life stages (instars) with mature
larvae reaching an average length of 1 1/2 inches (38 mm). After hatching,
the first instar larvae chew through the bark and the phloem (the inner
bark, the pipeline through which food is passed to the rest of the tree)
and into the cambium (the growing part of the trunk, located between the
bark and the sapwood).

As they feed (for several
weeks), the larvae wind back and forth. This creates the serpentine
(S-shaped) “galleries”, characteristic of this wood-boring beetle. The
galleries are filled with “frass”, a fine sawdust-like material. The final
galleries, which are generally from 4 inches to 20 inches (10 to 50 cm) in
length, extend from the phloem to the outer layer of the
sapwood.

Larval feeding ends by autumn, at which
time the fifth instar larvae overwinter in (1 cm) deep pre-pupal chambers
in the outer portion of the sapwood. Pupation generally

EAB gallery

takes place the following spring
(late-April to May), with adults staying in the pupal chambers for 1 to 2
weeks, at which time they emerge headfirst through a distinctive 1/8 inch
to 1/6 inch (3 mm to 4 mm) D-shaped exit hole, beginning the cycle of life
over again. The presence of the exit holes typically goes undetected until
trees show other, more visible symptoms of being
infested.

It should be noted that when EAB is
developing in healthy, newly infested ash trees whose defenses are still
strong and capable of retarding larval survival and growth, larvae may
need an additional 1 to 2 years before pupating and emerging as adults. As
larval densities increase, the 1-year life cycle becomes the norm.

D-shaped
emergence hole

Hosts

In the U.S. and
Canada, emerald ash borers only attack ash trees (the one exception being
privet, (Ligustrum Spp.)). The ash species of concern in NY are black
ash (Fraxinus nigra), green ash (F. pennsylvanica), and white
ash (F. americana).

Black ash (F.
nigra)

Green ash (F.
pennsylvanica)

White ash (F.
americana)

Signs of Infestation

Early detection of EAB in newly infested trees can prove
very difficult, particularly for the lay property or woodland owner as the trees
tend to exhibit few, if any, visible external symptoms of infestation. One of
the first noticeable signs of infestation is often the presence of unusually
abundant uneven holes drilled by woodpeckers as they feed on prepupal larvae
[note: this symptom is not exclusive to EAB infestation].

A very clear indication of EAB
infestation is the presence of the D-shaped emergence holes chewed through
the bark on branches or the trunk by adults when they emerge in the
spring. These holes are 1/8 inch (3 mm) in diameter. If the holes are not
D-shaped, then they were not caused by EAB (native wood borer emergence
holes are round or oval and are much larger, 1/4 inch (6 mm) or
larger).

D-shaped
emergence holes

Split
bark (gallery visible beneath)

Thin, 2 to 5 inch (5 to 12 cm) long vertical
splits through the bark of living trees [again, this sign is not exclusive
to EAB infestation]. In the event of EAB infestation, the splits may form
over the feeding galleries. If the bark is removed and frass-filled
serpentine, S-shaped galleries are found tunneled just beneath the bark or
etched into the underside of the bark, this is a sign of EAB infestation
[common native borers that infest ash trees bore into the
sapwood].

The presence of white to cream-colored, legless, flattened, 10-segmented, 1
to 1 1/2 inch (25 to 38 mm) long larvae found in the galleries beneath the bark
of living ash trees is another sign of the presence of emerald ash borers.

Canopy
thinning due to EAB

As the density of EAB infestation in an ash tree increases, the tree’s
foliage will wilt, branches start to die back, and the tree canopy will
thin out. Several years of infestation will cause many trees to lose 30 to
50 percent of their summer canopy. Trees may die after 3 to 4 years of
heavy infestation [note: canopy thinning and top dieback followed by tree
mortality is not necessarily a sign exclusive to
EAB].

Epicormic
shoots

Another sign of possible EAB infestation (but not limited to EAB) is
the sprouting of epicormic shoots around the base of the tree or at the
junction of live and dead parts of the trunk or branches. Epicormic shoots
or sprouts are stems and suckers that often appear in trees due to stress
or injury (such as defoliation or die-back) as a way for the tree to
compensate for the loss of productive leaf surface. Certain species, such
as oak and basswood are more prone to producing epicormic shoots than are
ash, so the formation of such shoots, combined with crown thinning or
die-back are a strong indication of EAB infestation.

Impacts of EAB
Infestation

Stressed ash trees are
more attractive to emerald ash borers than are healthy trees in the early stages
of an invasion. However, once EAB is established in an area, all ash trees
greater than 1 1/2 inch (3 cm) in diameter are susceptible to attack. EAB
infestation is always fatal to ash trees, even healthy ash trees, in
approximately 2 to 4 years.

EAB kills ash trees when the larvae
galleries damage the phloem, which is responsible for transporting nutrients
made during photosynthesis, and the xylem (sapwood), which is responsible for
transporting water and dissolved nutrients throughout the tree. This “girdling”
of the tree starves all parts of the tree beyond the galleries of nutrients and
water, killing the tree from the top down.

More than 40 million ash
trees have died or are dying from emerald ash borer attack in the United States
since the beetle’s introduction sometime shortly before its discovery in 2002.
More than 7.5 billion ash trees remain at risk.

In NY, ash was widely
planted to replace native elm trees that were killed by Dutch elm disease. In
some areas of the state, ash is a prevalent urban and suburban street tree. The
loss of large numbers of mature ash trees can have a devastating impact on the
urban and suburban canopy, leading to temperature changes, increased air
pollution, the economic impact of removing and replacing thousands of dead trees
in yards and along streets, and a potential public safety hazard and potential
liability issues of dead ash trees along streets and in parks and yards.

In natural forest settings, native ash trees are very common (white,
green and black ash make up almost 8% of all trees in NYS forests), providing
canopy habitat, and a good food source (seeds) for both birds and mammals.

Ash trees are valuable commercially, used for the
manufacture of flooring, furniture, and shipping pallets, as well as that
all-American device, the baseball bat. The almost 114 million board feet
of ash lumber grown annually in the eastern U.S. is worth about $25
billion. Black ash is important to the culture of Native Americans,
including NY’s Akwesasne, as it is used for traditional basket making.

Ash billet in baseball bat
factory

Management and
Control

The emerald ash borer is
unusually difficult to kill. Please see the “Emerald ash borer
general information and educational resources” page of this website for
information on managing and controlling EAB infestations.

Photo and
Graphic Credits

Close-up of
adult EAB - David Cappaert, Michigan State University,
Bugwood.org

Multi-state distribution map - Cooperative Emerald Ash Borer
Project; APHIS-PPQ, USFS

EAB trap - NYS DEC

Mixed larval stages -
David Cappaert, Michigan State University, Bugwood.org

Gallery - Joseph
O'Brien, USDA Forest Service, Bugwood.org

D-shaped emergence hole - David
R. McKay, USDA APHIS PPQ, Bugwood.org

Black ash - USDA-NRCS PLANTS
Database / Herman, D.E., et al. 1996. North Dakota tree handbook

Green
ash - Tom DeGomez, University of Arizona, Bugwood.org

White ash - Richard
Webb, Self-employed horticulurist, Bugwood.org

Emergence holes - Joseph
O'Brien, USDA Forest Service, Bugwood.org

Split bark - Pennsylvania
Department of Conservation and Natural Resources - Forestry Archive,
Bugwood.org

Crown thinning - Jana Albers, Minnesota Department of Natural
Resources Archive, Bugwood.org

Epicormic shoots - Pennsylvania Department
of Conservation and Natural Resources, Forestry Archive, Bugwood.org

Ash
billet in baseball bat factory - Pennsylvania Department of Conservation and
Natural Resources, Forestry Archive,
Bugwood.org

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