Asian Longhorned Beetle Alert: What to Do This August

If you have maples, elms, willows, birches, or other hardwoods on your property, August is the month to pay close attention. The Asian Longhorned Beetle (ALB) — identified by USDA APHIS as a significant pest threat — is currently in the heart of its typical activity window, and the damage it causes can be severe enough to kill otherwise healthy trees.

Here's what you need to know this month, and exactly what steps to take right now.

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Why August Matters for This Threat

Based on typical timing patterns, the Asian Longhorned Beetle is most active from May through September, making August one of the most critical months in its seasonal cycle. Adult beetles are actively emerging, feeding, and laying eggs during this period. Meanwhile, larvae from earlier egg-laying events may already be tunneling deep inside trunks and branches — causing internal structural damage that isn't always visible on the surface until it's too late.

The combination of active adults and developing larvae in August means the threat is operating on two fronts simultaneously. Acting now, before populations grow or damage deepens, gives you the best chance of protecting your trees.

Check our seasonal forecast to stay updated on how conditions in your area may be affecting activity levels this month.

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What to Look For Right Now

The Asian Longhorned Beetle is a wood-boring insect that tunnels deep into trunks and branches, compromising the structural integrity and vascular health of hardwood trees. When inspecting your trees this August, keep an eye out for:

• Round exit holes in the bark, approximately the size of a dime, where adult beetles have emerged
• Sawdust-like frass (wood shavings and excrement) accumulating at the base of a tree or in bark crevices
• Oozing sap or weeping wounds on the trunk and major branches
• Shallow oval or round egg-laying sites where bark appears scraped or pitted
• Adult beetles — they are large (typically 1–1.5 inches), glossy black with white spots, and have distinctively long, banded antennae
• Yellowing, wilting, or prematurely dropping leaves on otherwise mature trees
• Broken or dying branches that seem inconsistent with the overall health of the tree

If you're unsure what you're seeing, use our diagnosis tool to help identify the issue, or read the full details on Asian Longhorned Beetle for more information.

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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 afford to be complacent. Whether you're in the Northeast, the South, the Pacific Coast, or the Mountain West, hardwood trees in your area may be at risk during this peak activity period.

Because this pest has been flagged nationally by USDA APHIS, it's worth being especially vigilant if you live near areas with dense hardwood populations, urban tree canopies, or recent reports of infestations in your county or region.

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What to Do This Month

August's active conditions make timing critical. Here are the three primary actions to take right now:

1. Targeted Insecticide Application If you have confirmed or strongly suspected activity on your property, applying an appropriate insecticide can be effective — but timing is everything. Treatments are most effective when applied during the vulnerable larval or adult emergence stage, which aligns with right now. Always follow label directions carefully, and consider consulting a professional to ensure the correct product and application method for your specific trees and situation.

2. Biological Control Agents For a more ecologically integrated approach, natural predators and parasitoids can help suppress populations. Options include encouraging or introducing predatory beetles and parasitic wasps that target wood-boring insects. This approach works best as part of a broader management strategy rather than as a standalone solution.

3. Infested Material Removal If you identify infested branches, prune and destroy the material promptly. Remove fallen debris, as it can harbor eggs and larvae. Critically, do not move infested wood to other locations — dispose of it on-site or per local guidelines to avoid spreading the pest to new areas.

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When to Call an Arborist

Some situations go beyond what a homeowner should handle alone. Contact a certified arborist if:

• You find multiple exit holes or widespread frass across a tree
• A tree shows significant dieback or structural instability
• You're unsure of the identification and want a professional assessment before treating
• The affected tree is large, near structures, or poses a safety risk
• You want guidance on preventive treatments for high-value trees not yet showing symptoms

Early professional intervention can mean the difference between saving a tree and losing it. Use our find an arborist directory to connect with a certified professional in your area today.

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Don't wait for obvious damage to take action. August is the time to inspect, assess, and respond — your hardwood trees will thank you for it.