Asian Longhorned Beetle: What Homeowners Must Do This August

If you have hardwood trees 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 in the heart of its typical activity window, which runs from May through September. Right now, this destructive insect is at or near peak activity across the country, and the damage it causes can be severe enough to kill otherwise healthy trees.

Here's what you need to know this month.

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Why August Matters for This Threat

The Asian Longhorned Beetle follows a seasonal pattern that typically spans late spring through early fall, with activity peaking during the warmest summer months. August falls squarely in the middle of that window, meaning adult beetles are actively emerging, feeding, and laying eggs right now. Larvae that hatch from those eggs will tunnel deep into trunks and branches — a behavior that disrupts the tree's ability to move water and nutrients and can cause structural failure over time.

Because the most damaging activity happens beneath the bark and out of plain sight, many homeowners don't realize there's a problem until serious harm has already been done. Acting during August — while adults are visible and active — gives you the best chance to catch an infestation early and respond effectively.

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What to Look for Right Now

The Asian Longhorned Beetle targets hardwood trees, so if you have maple, elm, willow, birch, horse chestnut, or similar species, make them a priority for inspection this month. Walk your property and examine trunks and major branches carefully. Key signs associated with this pest include:

• Round exit holes in the bark, roughly the diameter 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 bark crevices
• Shallow, oval or round egg-laying sites in the bark where females have chewed depressions to deposit eggs
• Sap weeping from small wounds on the trunk or branches
• Yellowing, wilting, or dropping leaves on branches that appear otherwise intact
• Dead branches scattered through the canopy in midsummer, when healthy trees should be fully leafed out

Not sure what you're seeing? Use our diagnosis tool to document your observations and get guidance.

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Where It's Active

This pest is currently being tracked as active across all 50 U.S. states. Whether you're in New England, the Pacific Northwest, the Deep South, or the Great Plains, your hardwood trees may be at risk this season. National reach like this makes local vigilance especially important — don't assume your region is exempt.

For a current, state-by-state look at activity levels in your area, check the seasonal forecast.

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What to Do This Month

If you spot signs consistent with Asian Longhorned Beetle, or simply want to be proactive, here are the recommended steps to take in August:

1. Apply a Targeted Insecticide Timing is critical with this pest. August is one of the most effective windows for treatment because adult beetles are actively emerging and larvae are in vulnerable stages. Apply an appropriate insecticide following all label directions carefully. When in doubt about product selection or application method, consult a licensed professional.

2. Remove and Destroy Infested Material Prune out any branches that show clear signs of infestation. Infested wood and fallen debris can harbor eggs and larvae, so do not leave cut material on the ground near healthy trees. Dispose of it well away from your property — ideally by chipping, burning (where permitted), or bagging for municipal collection.

3. Support Natural Controls Where appropriate, biological control options — including encouraging natural predators and parasitoids in your landscape — can complement other treatment strategies. This is a longer-term approach best discussed with a professional.

4. Document and Monitor Take dated photos of any damage or suspected beetle sightings. This record will help track whether the problem is worsening and will be valuable if you involve a certified arborist or report the pest to your local USDA APHIS office.

For a full breakdown of treatment options and pest biology, visit the full details page.

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When to Call an Arborist

Some situations go beyond DIY management. Contact a certified arborist promptly if:

• You find multiple exit holes, significant frass, or widespread canopy dieback
• The affected tree is large, mature, or structurally important to your property
• You're unsure whether what you're seeing is actually Asian Longhorned Beetle
• The infested tree is near a structure, utility line, or high-traffic area where branch failure would be hazardous
• Previous treatments haven't produced visible improvement

A certified arborist can accurately diagnose the problem, recommend the right insecticide and application method, and help you make informed decisions about whether a tree can be saved or needs to be removed safely.

Find a certified arborist near you through our professional directory.

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August is the time to act. A few hours spent inspecting your hardwood trees today could mean the difference between a healthy canopy and a costly loss. Don't wait for the damage to become obvious — by then, the beetles have already done their worst work underground.