Emerald Ash Borer in New Hampshire: What to Do With Your Ash Tree
Emerald ash borer has been confirmed in Nashua since 2019 and in Amherst since 2017. If you own an ash, the choice is narrower than it looks: treat it on a schedule for as long as you keep it, or take it down while it is still cheap to take down.
Get a Local Callback
Name, number, town — details can wait.
Last checked: August 6, 2026 • Pest status from NHBugs; town list updated September 24, 2025
Where This Stands in August 2026
Emerald ash borer was first found in New Hampshire in Concord in March 2013. NHBugs — the pest site run jointly by UNH Cooperative Extension, the Division of Forests and Lands and the Department of Agriculture, Markets and Food — has kept the town list ever since. For the six towns this site covers it reads: Amherst 2017, Hollis 2018, Nashua 2019, and Hudson, Merrimack and Litchfield in 2020. That page was last updated September 24, 2025; we read it as of August 2026.
You will see 2014 in print — a Granite Geek column in the Concord Monitor on August 3, 2026 puts the arrival there. Every state and Extension source says March 2013.
There are three moves available with an ash here: treat it and keep treating it, take it down now, or take it down later at a higher estimate. The thresholds that sort those are published and specific, and almost nobody selling tree work quotes them.
Where the Beetle Actually Is
NHBugs publishes detections town by town, and as of that September 24, 2025 update the list reaches Berlin, Gorham, Jefferson, Randolph and Lancaster, each detected in 2024. What it does not publish is a statewide total, so there is no total here either.
- Amherst — 2017. Earliest of the six towns here.
- Hollis — 2018.
- Nashua — 2019.
- Hudson, Merrimack and Litchfield — 2020.
- Source: NHBugs, NH Towns With EAB Infestations, updated September 24, 2025; read as of August 2026.
The Quarantine Everyone Gets Wrong
Most of what is written about EAB quarantines describes rules that no longer exist, and there were two. The federal domestic quarantine — USDA's rule on moving ash material out of infested areas — was removed effective January 14, 2021. New Hampshire's own in-state quarantine on ash logs, chips, nursery stock and hardwood firewood was eliminated by the Department of Agriculture, Markets and Food in 2018; the UNH Extension notice went up in October 2018 and gives no precise effective date, so this page gives none either. NHBugs states the position now in one sentence: "Movement of ash wood and ash wood products is no longer regulated within New Hampshire." What is still in force is a firewood rule, and it is not an ash rule.
- Out-of-state firewood is prohibited from New Hampshire unless it is labeled as certified heat-treated — 140°F (60°C) for 60 minutes. In place since July 2011. (NHBugs, as of August 2026.)
- Ash moves freely inside the state — but NHBugs still recommends keeping ash firewood within about five miles of where it was cut, or seasoning it on site at least a year first. That is a recommendation, not a law, and it is not written here as one.
Is It Ash, and Is It Infested?
Most pages hand you a confident field key here — branching pattern, exit-hole shape, what the wood looks like under the bark. There isn't one on this page, because the New Hampshire sources behind it do not publish one and a key we invented would be worth nothing to you. What is published is the threshold that decides what happens next, and it is measured in crown dieback rather than in beetles. New Hampshire's guidance is that ash with greater than 50% crown dieback, or dead, should be removed rather than treated; past that point the tree can no longer move an insecticide around effectively (NHBugs, Using Insecticides, as of August 2026). The Purdue Landscape Report, in a January 22, 2019 piece on removal timing, draws the line earlier: under 30% canopy loss, treat; over 30%, plan the removal. For the identification itself, NHBugs takes homeowner reports through its own reporting form, and an ISA Certified Arborist — voluntary here, and the credential worth asking about — can put a written assessment in your hand.
Treat or Remove, and What Treatment Commits You To
New Hampshire's guidance is permissive, and the wording carries the weight. NHBugs says that when you find yourself within ten miles of an EAB outbreak and have ash you want to save, consider starting semiannual treatments of systemic products. Consider — not must. Every town here sits well inside that window, so the decision is live for every ash in the service area; that is not the same as saying treat.
- The chemistry. NHBugs describes emamectin benzoate, delivered by trunk injection, as giving better killing power over a longer period than the other active ingredients. It does not say how long, so no duration appears here.
- The commitment. Treatment protects a tree; it does not cure it. Keeping an ash alive means re-treating on a cycle for as long as you own the house. Stop, and the beetle is still in the neighborhood.
why delaying the same tree changes the work
The One License New Hampshire Does Issue
Nashua Services Related to This Guide
Working Out What to Do With an Ash?
Send the town, roughly how tall the tree is, and how much of the crown has gone bare. A site visit should document the complete scope in writing.
Ash and EAB Questions
Can I still move ash firewood in New Hampshire?
Inside the state, yes — NHBugs' wording is that movement of ash wood and ash wood products is no longer regulated within New Hampshire, and the federal domestic EAB quarantine was removed effective January 14, 2021. What is still enforced is the ban at the state line: firewood of out-of-state origin is prohibited unless labeled as certified heat-treated to 140°F for 60 minutes, in place since July 2011. (NHBugs, as of August 2026.)
My ash still looks healthy. Is there anything to do right now?
There is a decision to make, which is not the same as work to do. New Hampshire's guidance is to consider starting treatment once you are within ten miles of a known outbreak and have an ash you want to keep, and every town on this site is itself infested. A full canopy is also not proof of a sound trunk: the Purdue Landscape Report (January 22, 2019) found structural decline can begin while two thirds of the canopy is still intact. Doing nothing is legitimate — it is just a choice to remove the tree later, under worse conditions.
I read that wasps are beating the beetle. Should I wait?
Not for this tree. Biological control — parasitoid wasps released against EAB — is real, and the Concord Monitor reported on August 3, 2026 that New Hampshire's forest health staff are more optimistic about ash than they have been. But the aim of biocontrol is to reduce EAB pressure so ash can regenerate across a landscape over decades, not to rescue one infested tree in one back yard. It does not move the crown-dieback thresholds above.
Ask About an Ash Tree
Leaning, dropping limbs, dead down one side, or too close to the wires — describe the tree, what sits below it, and your timing.
What Else Ends Up on the Same Work Order
Removal is one line on a longer list: the pruning, the stump, the brush pile, and the back lot nobody has touched in thirty years.