Asian Longhorned Beetle Is at Peak Activity This August — Here's What Homeowners Need to Do

If you have hardwood trees on your property, August is the month to pay close attention. The Asian Longhorned Beetle (ALB) — identified by the USDA APHIS as a significant pest threat — is currently in the heart of its typical activity season, and the damage it causes can be severe and long-lasting. Acting now, while the threat is active, gives you the best chance of protecting your trees.

Check our seasonal forecast for the latest pest pressure updates in your area.

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Why August Matters for Asian Longhorned Beetle

The Asian Longhorned Beetle follows a typical activity window that runs from May through September, with summer months representing the core of adult activity. August sits squarely in the middle of that window, making it one of the most critical months to inspect your trees and take action if needed.

What makes this pest particularly destructive is its life strategy: adults lay eggs beneath the bark of hardwood trees, and the larvae that hatch tunnel deep into the wood of trunks and branches. This internal damage disrupts the tree's ability to transport water and nutrients, often causing structural weakness and dieback that isn't immediately visible from the outside. By the time obvious symptoms appear above ground, significant harm may already be done underground the bark.

Because the beetle is active as both adults and larvae during August, treatment timing right now can be especially effective.

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What to Look for Right Now

Getting outside and physically inspecting your hardwood trees this month is one of the most valuable things you can do. When walking your property, keep an eye out for:

• Adult beetles on or near hardwood trees — ALB adults are large, distinctive beetles with long, banded antennae, typically black with white spots
• Round exit holes in the bark, roughly the size of a dime, where adult beetles have emerged
• Sawdust-like frass (wood shavings mixed with excrement) accumulating at the base of the tree or in branch crevices
• Weeping sap or discolored bark at entry or exit points
• Branch dieback or crown thinning that seems out of season

Not sure what you're seeing? Use our diagnosis tool to help identify symptoms and get guidance on next steps.

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Where It's Active

This pest is currently tracked as active across all 50 states, meaning no region of the country can consider itself off the hook. Whether you're in the hardwood-rich forests of the Northeast, the oak-studded South, or the urban tree canopies of the Midwest and West Coast, your trees may be at risk during this active period.

Hardwood species are the primary targets — trees like maple, elm, willow, birch, poplar, and ash are among those most commonly affected. If these species are present on your property, they deserve a careful look this month.

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What to Do This Month

Taking action in August, while the pest is active, gives you the most leverage. Here are the three key approaches recommended for managing Asian Longhorned Beetle:

1. Targeted Insecticide Application Applying an appropriate insecticide during the active adult emergence and larval stage — right now — is one of the most effective interventions available. Timing is critical: treatments applied during this window have the greatest chance of reaching vulnerable life stages. Always follow label directions carefully, and consider consulting a licensed professional to ensure the right product is used correctly.

2. Biological Control Agents For homeowners looking for lower-chemical options, encouraging or introducing natural predators and parasitoids can provide meaningful support. This includes parasitic wasps and predatory beetles that target ALB. In some situations, applications of Bacillus thuringiensis (Bt) may also be relevant. Discuss these options with a certified arborist to determine what's appropriate for your specific situation.

3. Infested Material Removal If you identify infested branches, prune and destroy the affected material promptly. Remove any fallen debris, deadwood, or plant material from around your trees that could harbor eggs or larvae. Critically, dispose of this material away from healthy trees — don't chip or move it to another part of your yard or a neighbor's property without proper treatment.

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When to Call an Arborist

Some situations call for professional eyes and professional tools. You should find an arborist and schedule an inspection this month if:

• You've found exit holes, frass, or adult beetles on your trees
• You have mature hardwood trees with high structural or aesthetic value on your property
• You're unsure whether what you're seeing is ALB or another pest
• You want to apply systemic insecticides, which require proper licensing and equipment in many states
• A tree is showing significant crown dieback or structural decline

An ISA Certified Arborist can assess your trees, confirm identification, and recommend a treatment plan tailored to your property. Early professional intervention often means the difference between saving a tree and losing it.

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Don't wait for obvious decline to take action. August is your window — use it. For full details on identification, life cycle, and treatment options, visit the Asian Longhorned Beetle pest profile on TreeIssues.com.