Asian Longhorned Beetle in August: What Homeowners Must Do Now

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 currently in the heart of its typical activity window, and the damage it causes can be severe and permanent. Here's what you need to know right now, and exactly what steps to take this month.

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Why August Matters for This Threat

The Asian Longhorned Beetle follows a typical activity window spanning May through September, which means August sits squarely in the peak of its season. During these warm summer months, adult beetles are actively emerging, feeding, and laying eggs inside the wood of hardwood trees. The larvae that hatch tunnel deep into trunks and branches, disrupting the tree's ability to move water and nutrients — damage that often isn't visible until it's already extensive.

Because August represents a critical period in the beetle's life cycle, actions you take this month can meaningfully interrupt that cycle before populations build further heading into September. Waiting until fall to investigate or treat is often waiting too long.

Check our seasonal forecast to stay current on threat levels in your region throughout the rest of the summer.

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What to Look For Right Now

Early detection is your most powerful tool. Walk your property this month and inspect your hardwood trees carefully. Because this pest tunnels inside the wood, some signs are subtle — but there are physical clues to watch for on the outside of your trees:

• Round exit holes in the bark where adult beetles have emerged (typically about the size of a dime)
• Sawdust-like frass (wood shavings mixed with excrement) collecting at the base of the tree or in bark crevices
• Shallow oval or round scars on the bark where females have chewed sites to deposit eggs
• Weeping sap or staining on the trunk surface
• Dying or dead branches in the upper canopy, sometimes called "flagging"
• Adult beetles — large, glossy black insects with distinctive white spots, and very long banded antennae

Not sure what you're seeing? Use our diagnosis tool to help identify whether these symptoms match Asian Longhorned Beetle or another concern.

For a complete description of this pest and its biology, visit the full details page.

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Where It's Active

This pest is currently reported as active across all 50 states, meaning no region of the country should consider itself off the hook this August. Whether you're in the Pacific Northwest, the Gulf Coast, New England, or the Great Plains, hardwood trees in your landscape may be at risk. Maples, ashes, elms, birches, willows, and several other hardwood species are among the trees known to be vulnerable to this pest.

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What to Do This Month

If you suspect or confirm Asian Longhorned Beetle activity, here are the three primary management approaches to consider in August:

1. Targeted Insecticide Application Apply an appropriate insecticide following all label directions carefully. Timing is critical — treating during the vulnerable larval or adult emergence stage, which is happening right now, offers the best chance of effectiveness. Contact a licensed professional if you are unsure which product or method is appropriate for your situation.

2. Remove and Destroy Infested Material Prune and remove infested branches promptly. Dispose of all infested wood, fallen debris, and plant material away from healthy trees — do not chip or compost it on-site if beetle activity is confirmed. This step is essential to preventing the spread of eggs and larvae to neighboring trees.

3. Encourage Biological Controls Where appropriate, natural predators and parasitoids can play a supporting role in managing beetle populations. Options include encouraging predatory beetles, parasitic wasps, or — for applicable life stages — applying Bacillus thuringiensis (Bt). This approach works best as part of an integrated strategy, not as a standalone solution.

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When to Call an Arborist

Some situations call for professional eyes and hands. Contact a certified arborist if:

• You find confirmed exit holes or egg-laying scars on your trees
• A tree is showing significant canopy dieback or structural decline
• You are unsure whether a tree can or should be saved
• You need help with safe removal of heavily infested limbs or trees
• You want a professional insecticide application done correctly and safely

Asian Longhorned Beetle is a federally recognized pest threat, and in some areas its presence triggers regulatory response. A certified arborist can help you understand your obligations and options.

Find a qualified arborist in your area through our professional directory to get an assessment before the season advances further.

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August is the time to act — not to wait and watch. A few hours spent inspecting your hardwood trees this month could make the difference between early intervention and losing a mature tree that took decades to grow.