A guide to Florida’s commonbark and ambrosia beetles

Craig Bateman1 & Jiri Hulcr1,2

1UF/IFAS School of Forest Resources and Conservation,2Entomology and Nematology DepartmentImages: J. Hulcr, T. Atkinson, C. Bateman, Z. Nolen, or ForestryImages.org

FOR 321, Revised March 2017. Reviewed March 2020

This guide provides an introduction to the biology and identification of Florida’s bark and ambrosia beetles.

• What are bark and ambrosia beetles?.......................................3

• Where can I find the beetle….....................................................4

• How to use this document……………………………..……5-6

• Species descriptions………………………………………...7-33

• Beetle morphology………………………………………...34-35

• More resources………………………………………………...36

Contents (click to jump):

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What are bark and ambrosia beetles?

Bark and ambrosia beetles are a highly diverse group of forest insects. Most live peaceful lives inside dead or dying trees. The beetles help fungi reach normally inaccessible nutrients by burrowing into newly dead trees and together they begin the process of decay in the tree.

Why do bark beetles matter?A few species of bark beetles, or fungi they carry, can contribute to major diseases in trees. These diseases can cause major disruptions to forest ecosystems, and the loss of valuable wood and tree products.

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• Bark or ambrosia beetles are found in every forest on earth.• Trees containing bark beetles often have sawdust or sap on the outside:

• Ambrosia beetles push compact noodles of sawdust outside the tree:

Where can I find the beetles?

You can trap beetles in a forest near you. Find out more from the Backyard Bark Beetles project.4

How to use this document

All have elbowed (bent) antennae with a large round club at the end:

First, make sure you have either a bark or ambrosia beetle:

All have a large, round head, often partly hidden inside their pronotum:

xyleborini.myspecies.info

pronotum

head

antennal club

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How to use this document

If there is a page for identifying a tribe or genus containing a species, use that first.

If there’s a word you don’t know, check the morphology page by clicking the link in the upper right corner.

If you think you have a match, check the ID characters using a microscope.

tribegenus species

Next, simply scroll through the slides to see what looks right.

That’s it! Now you can compare your specimen to the following slides and see what you find.

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Subfamily SCOLYTINAE

Species descriptions of Florida’s common bark and ambrosia beetles:

Corthylini Monarthrum maliGnathotrichus materiarius

Xyleborini Ambrosiodmus spp.Cnestus mutilatusEuwallacea spp.Xyleborinus saxeseniiXyleborus affinis Xyleborus ferrugineus Xyleborus pubescensXyleborus glabratus Xylosandrus amputatusXylosandrus crassiusculus Xylosandrus compactus

Subfamily PLATYPODINAE

HylastiniHylastes spp.

HylurginiDendroctonus terebrans Dendroctonus frontalis

IpiniIps avulsusIps grandicollisIps calligraphusOrthotomicus caelatus

PityophthoriniPityophthorus spp.

Cryphalini Hypothenemus spp. Myoplatypus flavicornis

Euplatypus compositus

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ID Characters:

NativeHost tree: conifers

Curculionidae

Scolytinae

Hylurgini & Hylesinini

• Top of pronotum flat.1

• Front edge of elytra curved and with rounded bumps/teeth. Bugguide.net

1

Jump to morphology

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ID Characters:

NativeSometimes pests of live pines

Curculionidae

Scolytinae

HylurginiDendroctonus genus

• Head always visible from above.

D. terebrans: Black turpentine beetleour largest bark beetle, 5-8mm.

D. frontalis: Southern pine beetletiny, 2-3mm.

Jump to morphology

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ID Characters:

NativePrimarily in pine roots

Curculionidae

Scolytinae

HylesininiHylastes genus

• Head mostly invisible fromabove (compare Dendroctonus).

Jump to morphology

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H. salebrosus -less hair, broad

H. tenuis-hairy, skinny

ID Characters:

NativeSometimes pests of pines

Curculionidae

Scolytinae

IpiniIps genus

• Segments of antennal club wavy.• Elytra declivity excavated and with large teeth.• I. avulsus: 2.1-2.8 mm• I. grandicollis: 2.9-4.6 mm• I. calligraphus: 3.8-5.9 mm

Jump to morphology

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I. avulsus, I. grandicollis, I. calligraphus(males only)

ID Characters:

NativeHost tree: pines

Curculionidae

Scolytinae

IpiniOrthotomicus caelatus

• Antennal sutures curved inward.• Bottom of elytra declivity flat, no ridge like in Ips.

Jump to morphology

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ID Characters:

Native & exoticHost tree: diverse

Curculionidae

Scolytinae

Cryphalini (pygmy borers)Hypothenemus genus

• The smallest bark beetles, no longer than 1.2 mm• Hairy or scaly. • Very noticeable bumps or teeth on pronotum.

Jump to morphology

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H. birmanus

H. seriatus

H. eruditus

ID Characters:

NativeHost tree: diverse

Curculionidae

Scolytinae

PityophthoriniPityophthorus genus

• All small.• Often hairy on frons. • Antennal club small, flat, sutures curved.• Layered curves on pronotum.

Jump to morphology

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ID Characters:

NativeHost tree: diverse

Curculionidae

Scolytinae

Corthylini

• Eye deeply notched, ie: • Elongate, especially the pronotum.• Sides of pronotum with a fine raised line.• Antennal club large, flat, with three clear sutures.

Jump to morphology

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ID Characters:

NativeHost tree: broadleaf

Curculionidae

Scolytinae

CorthyliniMonathrum mali

• Elongate, especially the pronotum. • Elytra shallowly impressed along the middle, deeply at declivity.

Jump to morphology

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ID Characters:

Curculionidae

Scolytinae

CorthyliniGnathotrichus materiarius

• Shining, no hair. • Elytral declivity rounded and pointed at the end.• Sutures of antennal curved outward.• Fine raised line on the top of pronotum.

NativeHost tree: conifers

Jump to morphology

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ID Characters:

Curculionidae

Scolytinae

Xyleborini

• Eye notched.• Antennal club mostly type 1 and 2, sutures curved inward.• Protibia wide and flat, and armed with teeth.• Most of the ambrosia beetles!

Jump to morphology

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ID Characters:

Curculionidae

Scolytinae

XyleboriniAmbrosiodmus genus

• Wide, pointed scales covering entire pronotum.1

• Steep elytral declivity.

Exotic & nativeHost tree: many, diverse

1 Jump to morphology

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ID Characters:

ExoticHost tree: many, diverse

Curculionidae

Scolytinae

XyleboriniEuwallacea genus

• Bulky, dark.• Declivity gently sloped.

Jump to morphology

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E. fornicatus (below) is the smallest species at 1.8 – 2.5 mm, and can range from brown to black

ID Characters:

ExoticHost tree: many, diverse

Curculionidae

Scolytinae

XyleboriniCnestus mutilatus

Jump to morphology

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• Largest ambrosia beetle in North America.• Abdomen much shorter than pronotum.

squished-looking abdomen

ID Characters:

ExoticHost tree: many, diverse

Curculionidae

Scolytinae

XyleboriniXyleborinus saxesenii

• Small knob surrounded by hair between pronotum and abdomen(all species of Xyleborinus).

• Antenna club type 1.

Jump to morphology

small knob

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ID Characters:

Exotic & nativeHost tree: many, diverse

Curculionidae

Scolytinae

XyleboriniXyleborus genus

• Elongate, mostly light-colored. • Antennal club type 1 or 2.• Posterocoxal process inflated (see below).

Jump to morphology

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ID Characters:

NativeHost tree: many, diverse

Curculionidae

Scolytinae

XyleboriniXyleborus affinis

• Dull, opaque (not shiny) elytral declivity when dry, with small bumps.

Jump to morphology

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ID Characters:

NativeHost tree: diverse, often in pines

Curculionidae

Scolytinae

XyleboriniXyleborus ferrugineus

• A pair of large projections on elytral declivity.• Usually dark red/brown.

Jump to morphology

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ID Characters:

NativeHost tree: many, but primarily pine

Curculionidae

Scolytinae

XyleboriniXyleborus pubescens

• Very similar to X. affinis, but declivity shining, steeper, and more rounded.

Jump to morphology

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ID Characters:

Exotic (Redbay Ambrosia Beetle)Host tree: Lauraceae (redbay, avocado, sassafras,…)

Curculionidae

Scolytinae

XyleboriniXyleborus glabratus

• Shining, dark colored.• Distinctly pointed tip of declivity. • Smaller than most Xyleborus.

Jump to morphology

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ID Characters:

All exotic

Curculionidae

Scolytinae

XyleboriniXylosandrus

• Bulky species. • Antennal club flat, truncated. • Procoxae separated (see yellow arrows).

Jump to morphology

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ID Characters:

ExoticHost tree: broadleaf, but mostly unknown

Curculionidae

Scolytinae

XyleboriniXylosandrus amputatus

• Truncated elytral declivity.

Jump to morphology

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ID Characters:

Exotic (Granulate Ambrosia Beetle)Host tree: many, diverse

Curculionidae

Scolytinae

XyleboriniXylosandrus crassiusculus

• Dull, opaque (not shiny) elytral declivity when dry, and without any large bumps.

Jump to morphology

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ID Characters:

Exotic (Black Twig Borer)Host tree: twigs of most broadleaf trees

Curculionidae

Scolytinae

XyleboriniXylosandrus compactus

• Tiny, black, with shiny declivity

Damage

Jump to morphology

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ID Characters:

NativeHost tree: hardwoods

Curculionidae

Platypodinae

Euplatypus compositus

• Female elytral declivity blunt. • Male declivity with two narrow, pointed projections.• Female & male pronotum with two small pores.• Very long leg segments (all platypodines).

female

male

Jump to morphology

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ID Characters:

NativeHost tree: pines

Curculionidae

Platypodinae

Myoplatypus flavicornis

• Female elytral declivity with blunt projection.• Male declivity with a more sharply pointed projection.• Very long leg segments (all platypodines).

male

male

male

female

Jump to morphology

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Modified after Hopkins 1909. Contributions toward a monograph of the scolytid beetles.

Important beetle morphology Last slide viewed

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Antennal clubs Last slide viewed

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Additional resources

Online Keys• Bark beetle genera of the US• Bark beetles of Louisiana• Key to Xyleborini of North America• Key to Xyleborini genera• S. Bambara's bark beetles of SE USA

Beetle Resources• Backyard bark beetles: Trap beetles and contribute to a citizen science program!• Interactive tool for identifying Damage by the Redbay ambrosia beetle• Tom Atkinson's bark beetles of Southeast USA• World's bark beetle pictures• The Xyleborini taxonomy database• xyleborini.myspecies.info: A collaborative ambrosia beetle database - you can join!

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