Asian Longhorned Beetle (ALB) (Anoplophora glabripennis, family Cerambycidae) is potentially the most devastating non-native pest to have ever arrived in North America. ALB kills trees belonging to 12 genera in 9 plant families, including all native maples (Acer spp.), a preferred host.

Asian Longhorned Beetle (ALB) in Ohio

Emerald ash borer (EAB) (Agrilus planipennis) kills native trees belonging to one genus, Fraxinus. If ALB were ever allowed to go the way of EAB in North America, it would be an ecological catastrophe, making EAB look like a walk in the park.

Successful eradication is essential to avoiding a catastrophic loss of trees on a scale never before seen in the U.S. The USDA Animal and Plant Health Inspection Service (APHIS) has declared August to be “Tree Check Month” to alert the public to check trees for ALB. August was chosen because it’s the time of the year in North America when we can typically see the maximum number of adults.

In 2011, an ALB infestation was discovered in S.W. Ohio in Clermont County. Since that time, our Ohio Department of Agriculture (ODA) has been on the front lines partnering with USDA APHIS to eradicate ALB from our state. Through surveying, quarantines, and tree removal, the unsung heroes of the Ohio ALB Eradication Program have been successful in gradually eradicating ALB. However, we must remain vigilant.

USDA - Ohio Department of Agriculture sign

USDA Climber Checking for ALB

ALB Quarantined Area sign

Early detection is critical to the successful eradication of ALB both in terms of time and money. There’s always a possibility that ALB may slip through our U.S. border interdiction efforts, meaning we must stay alert to ALB no matter where we live in Ohio or elsewhere in the U.S.

There’s Always a Risk

Stay Alert to ALB

ALB prefers maples. However, the beetles will also complete their development on Aesculus (horsechestnuts and buckeyes); Ulmus (elms); Salix (willows); Betula (birches); Platanus (Sycamore/Planetrees); Populus (Poplars); Albizia (Mimosa); Cercidiphyllum (Katsura); Fraxinus (ashes); Koelreuteria (goldenraintree); and Sorbus (mountainash).

Here are some tips for detecting ALB:

1. Focus on Maples: Although ALB will attack trees belonging to 12 genera, maples (Acer spp.) are by far the most preferred host. Finding evidence of ALB in live, healthy maple stems should be reported.

ALB Indicators

ALB Exit Hole

2. Branch Breakage: ALB larvae tunnel through and feed on the wood (xylem) of trees. This weakens branches, causing them to break. Unusually heavy breakage of healthy branches on maple trees should be investigated.

ALB Larval Tunneling in Xylem (Wood)

ALB Indicators

Branch Breakage from ALB Damage

ALB Stem Breakage Infested Trees Marked for Removel

3. Holes and the "Pencil Test": The big beetles typically emerge from deep inside the xylem, so the perfectly round adult emergence holes extend deep into the tree. Inserting a #2 pencil into the holes will reveal the depth of the emergence holes. However, trees may close the exit holes with wound-response tissue.

ALB Exit Tunnel Out of Xylem (Wood)

ALB “Pencil Test” with #2 Pencil - 1

ALB “Pencil Test” with #2 Pencil - 2

ALB Exit Hole Closed by Wound-Response Tissue

Closed Emergence Holes

4. Pits in the Bark: ALB females chew a concave pit through the bark to the xylem where they lay a single egg. However, trees may close the pits relatively quickly, so you may only see rounded wounds. Newly created "oviposition pits" may also weep sap, staining the bark for a short time, but this symptom is inconsistent and is most apparent on smooth bark.

ALB Female Chewing Oviposition Pit

ALB Oviposition Pits

Bark Stripped Showing ALB Oviposition Sites

ALB Adult First Instar Larva

Sap Oosing in Mid-Summer from ALB Oviposition Pits

5. Woodpecker Damage: ALB larvae live deep inside the xylem. Woodpeckers excavate deep holes in search of these large, tasty ALB larval meat morsels. Finding deep woodpecker excavations on live maple stems with healthy-looking leaves would point to ALB.

ALB – Related Woodpecker Damage

6. Frass: ALB produces small wood shavings, called frass, as they emerge from trees or as the females chew oviposition pits.

ALB Frass

7. Bark Cracking: Larval feeding damage may stimulate trees to produce wound-response tissue beneath the bark that first consists of meristematic callous tissue then raised, lip-like woundwood. The woundwood lifts the overlaying bark producing cracks and fissures.

Woundwood Stimulated by ALB Larval Feeding Damage (Painted Red for Removal)

Bark Cracking Due to ALB Larval Feeding Damage

ALB Bark Cracking

8. Hulking Cream-Colored Larvae: Longhorn beetle larvae are called “Round-Headed Borers” owing to the rounded segment just behind the head. Native round-headed borer larvae are commonly found in stressed, dying, or dead stems. Finding such larvae in healthy maple stems could point to ALB.

ALB Larva Deep in the Xylem (Wood)

ALB Late Instar Larva

9. Big Beetles: ALB is a large beetle with distinct black and white markings. One of the common names for this beetle in China translates to the descriptive "starry night beetle."

ALB Female in Ohio

ALB Male in Ohio

ALB Male and Female Mating Pair

If you find beetles or any of these ALB indicators, report it. In fact, if you find ANY suspicious signs or symptoms, report it! There is no harm in reporting something suspicious, even if it's not ALB. However, there is great harm if it is ALB, and it's not reported. Reporting gives ALB professionals a chance to investigate.

Here are the ways you can report suspicious symptoms:

- Call the Ohio ALB eradication program office at 513-381-7180

- Send an email message to ALB@agri.ohio.gov

- Use the online “OH Dept. of Ag: Plant Pest Reporter Tool” at: https://survey123.arcgis.com/share/1b36dd2cf09e4be0a79776a6104ce1dc

NOTE: Always take pictures of the beetles, if possible. If beetles or larvae can be collected, place them in a jar and freeze them for identification.

Ron Wilson

In The Garden With Ron Wilson