Why is May considered tick season in New Hampshire?

Because nymphal blacklegged ticks emerge around mid-May and join adults that are already active, and nymphs are the life stage most responsible for Lyme disease locally. They're roughly the size of a poppy seed, which makes them easy to miss on skin or clothing during the hours of attachment it typically takes to transmit infection. New Hampshire has one of the higher Lyme case rates in the country, and roughly 60 percent of the state's blacklegged ticks sampled carry the bacterium that causes it, which is why this single change matters more than everything else moving in May combined.

Are boxelder bugs a problem in May?

No, and our own old calendar was wrong to list them as one. By May, any boxelder bugs that survived winter in a wall void have already left the structure and are outdoors laying eggs on host trees. They aren't aggregating on walls or trying to get inside — that behavior is a fall event, months away. A boxelder bug seen in a yard in May is doing exactly what it should be doing, on a tree, not at a home.

Why did raccoon and mite activity turn down in May if they seemed active in April?

Both were responding to a spring peak that has now passed. Raccoons finished their birthing peak in April and have shifted to daytime foraging with kits, which is quieter and less noticeable than the denning commotion of March and April. Clover mites hatched in their biggest generation of the year around April 1st, and by late May rising temperatures push past their comfort range, so the sunny-wall nuisance fades rather than continuing to build.

Do I need to do anything about mosquitoes yet in May?

Mosquito populations are building through May as the season ramps toward its June-through-October peak, which is also NH DHHS's active surveillance window for Eastern Equine Encephalitis (EEE) and West Nile virus — the same window that in 2024 produced New Hampshire's first human EEE cases in ten years — 2 human cases and 1 death, a fatal one in an adult from Hampstead and a Kensington case who survived — alongside seven EEE-positive mosquito batches statewide. May itself isn't the priority month, though — ticks are. If standing water hasn't been cleared around the property yet, doing so now is worthwhile ahead of summer and is the cheapest way to hold down the mosquito species that carry those viruses, but the single highest-value action this month is tick precaution: checking after time outdoors and maintaining a mown buffer between lawn and treeline, since nymphs are active and easy to miss.

Daniel Brady · NH-Licensed Pesticide Applicator · License #782664

|Reviewed by Daniel Brady

What Pests Are Actually Active in May in New Hampshire?

Shoulder monthThe season is turning — a few real changes, not many.

May turns down more than it turns up. Six species — beetles, boxelder bugs and their cluster, crickets, cluster flies, mites and raccoons — settle from their spring flicker into a quieter, fully-outdoor pattern. Only one species genuinely turns up: ticks, as nymphs emerge alongside already-active adults. That single change matters more than the other six combined, because nymphal ticks are the life stage most often responsible for Lyme disease in New Hampshire. Birds remain at their nesting peak from April. This is a moderately active month dominated by one real health story.

May at a glance

Species at peak: 2
Turned up: 1 newly active
Turned down: 6 winding down
The floor: 8 here year-round

~60%
Share of New Hampshire's sampled blacklegged ticks carrying the bacterium that causes Lyme disease
NH DHHS
2 human cases, 1 death
New Hampshire's 2024 EEE outbreak, the worst in a decade, driven by the mosquito species building through May
NH DHHS
7 batches
EEE-positive mosquito batches confirmed statewide in the 2024 season
NH DHHS

Where in the year

You are here · May

A pest year has a shape. This strip is the whole of it — the season you’re in, the months on either side, and the one you’re reading now.

The New Hampshire pest year

SpringYou are here · May

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

This monthSame seasonOther months2 at peak this month

Previous monthApril Next monthJune

The changelog

What changed in May

Not a list of seven pests re-served every month. A release log: what turned up, what wound down, what’s always here, and what isn’t here at all — 2 species at peak this month.

Turned up

newly active — more than last month

ticksPeak

Nymphal blacklegged ticks emerge around mid-May alongside already-active adults. Nymphs are the stage most linked to Lyme transmission in New Hampshire — small enough to go unnoticed, active through summer.

Do this · Check yourself, kids and pets after time in tall grass or at the woods edge. Keep lawns mown and maintain a clear buffer between lawn and treeline.

Turned down

winding down — you can stop worrying

beetlesDormant

Asian lady beetles are outdoors laying eggs on aphid-rich plants, functioning as a beneficial predator rather than a wall-massing nuisance. The indoor story is over until fall.