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Emerald Ash Borer

Agrilus planipennisFairmaire

(Coleoptera: Buprestidae)

A guide to identification and

comparison to similar species

Prepared by:

Gary L. Parsons

Department of Entomology, Michigan State University

November 2008

Introduction The adult stage of the Emerald Ash Borer (EAB) is fairly distinctive

and usually easy to tell apart from most similarly colored and shaped

buprestids and other insects by a trained taxonomist. However, many

researchers and field workers currently sampling for EAB are not

trained taxonomists, and might confuse some other similarly shaped

or colored insects with EAB. The species included in this guide were

chosen because of their relative commonness, similarity in size,

shape and/or coloration to the EAB, and because specimens were

available for photography in the A.J. Cook Arthropod Research

Collection, at Michigan State University. Additional species, not

included here, may be present in other parts of North America that

could also potentially be confused with the EAB.

How to Use This Guide

This guide is intended to assist insect diagnosticians and others

who have some familiarity in identifying insects. It’s use will be

easier if the user has at least a basic knowledge of insect

morphology and terminology and a basic familiarity with insect

orders, families, and genera.

The main purpose of this guide is to assist with sight identification of

adult specimens that have been field collected or reared. It will be

somewhat easier to verify the identity of beetles reared from known

hosts, however host data is not necessary to use this simple guide.

Many trapping methods for EAB utilize Tanglefoot®, Pest-Stick® or

some other kind of sticky material. To be able to properly identify

specimens, all residues of this sticky material must be removed with a

suitable cleaning agent. Soaking beetles in 95% ethanol will dissolve

Tanglefoot, and Histoclear® will dissolve Pest-Stick. It may take

several days of soaking and frequent transfers to clean solvent to

remove all traces of the sticky material. In addition, specimens in

alcohol usually do not appear their true color or show setae and setal

patterns while wet. Ideally, specimens should be cleaned and allowed

to air dry. Specimens mounted on pins or points will usually be much

easier to manipulate under a dissecting microscope, which is usually

needed for best examination of these small beetles. The bright lighting

typically used with microscopy will best reflect the coloration of these

beetles for comparison to the pictures used in the guide.

Note the similarity in color among the beetles in the photos to the left that were

removed from sticky traps and pinned without any cleaning. The photos to the

right are the same beetles after cleaning for only a few seconds with hexane

used as a solvent. While still not perfectly clean, sufficient color and patterns

now are evident to allow these to be identified to species.

Agrilus

anxius

Agrilus

bilineatus

Agrilus

cyanescens

The initial pages of this guide describe the general characteristics for

identification of the emerald ash borer. These are followed by pages showing

some additional species of Agrilus, other Buprestidae, and a few other beetles

that have similar color and/or shape to the EAB, and which could potentially

be confused with it.

These pages can be used for basic sight comparison and possible

identification of some of the more common species in question. This guide

uses coloration differences and a few distinctive, morphological characters for

comparisons. Those using this guide should not expect to be able to identify

any given specimen with absolute certainty to the species level. There are

171 species of Agrilusin North America, and only a few representatives are

shown here. Many of the smaller species are very similar to each other, and

most can only be reliably identified with keys. There are a few keys for North

American Agrilus

(Fisher 1928, Bright 1987, Downie & Arnett 1996 for eastern species)

and

other Buprestidae that can be used for identification of difficult specimens.

However, it may still be necessary to send difficult specimens to an expert

with familiarity in this group of insects. There are currently no revised keys

available to North American Agrilusor other Buprestidae that include the

EAB.

An example of a species comparison to EAB

as used in this guide

Agrilus bilineatus(Weber) “two-lined chestnut borer”

• Length: 4.2-9.5 mm, slightly smaller than EAB.

• Distinctively colored bronze-black with white-

yellow pubescent stripes extending from

edges of pronotum backwards along length of

elytra

(only visible on dry specimens).

• Abdominal dorsum black in color

(red in EAB)

,

pygidium with carina and projecting spine

(similar to EAB)

.

• Hosts: oaks, chestnut, American hornbeam,

beech, and eastern hop hornbeam.

1. Scientific and common name

(if available) of the species

being compared to EAB.

2. Side-by-side comparison of

the species to EAB at the

same size scale.

3. Text box listing size range,

description of color and shape,

similarities and differences to

EAB, and known host plants.

4. Side, top and oblique views of

the species showing color and

shape characteristics.

5. Photos of the most diagnostic

characteristics that will aid in

separation of the species from

EAB.

6. Range map of the species.

12

6

54 3 bilineatuswith

carina/spine dorsum

of abdomen blackEAB with

carina/spine dorsum

of abdomen red Source of morphological characteristics, host records and

distributional data primarily from Bright 1987, Downie & Arnett

1996, and Fisher 1928.

Family:

Buprestidae

“metallic wood-boring beetles”

The genus Agrilusis one of 53 genera of Buprestidae found in North America.

Fortunately, species in the genus Agrilushave a very distinctive shape that will

easily separate them from most of the other common genera of Buprestidae.

Agrilusin general are more linear and cylindrical than other genera of Buprestidae

and the base of the prothorax is produced backward as a lobe, which is lacking or

less obvious in most other genera

(except Brachysand Chrysobothris)

.

Agrilus(EAB)

Anthaxia

Cypriacis

Pronotum in Agrilus

produced backward as

lobe

Agrilusare more

elongate and cylindrical

than other Buprestidae Note: specimens

are not all to the

same size scale

Acmaeodera Brachys Buprestis Chalcophora Chrysobothris

Dicerca

Melanophila/

Phaenops

Chrysophana

Identification of the

Emerald Ash Borer

Agrilus planipennisFairmaire

“emerald ash borer” (EAB) • Typical specimens are a bright, metallic, emerald

green color overall, with the elytra usually

appearing somewhat duller and slightly darker

green. The overall greenish coloration may also have

variable amounts of brassy, coppery or reddish

reflections, especially on the pronotum and ventral

surfaces.

• A few rare specimens of EAB are entirely coppery-

red, entirely bluish-green, or green with bluish elytra.

• Length:
• EAB in general is

somewhat larger in size

and more brightly metallic

green than most other

U.S. Agrilusspecies.

dorsal view ventral view

x

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