What's Eating Your Mint?

Mentha spp.

Reviewed by Kiersten Rankel M.S.

Quick Answer

For mint, the most likely culprits are aphids clustering on new growth tips and flower spikes, four-lined plant bug leaving distinctive sunken pinhole spots across the leaves, and spider mites in hot dry weather or on stressed indoor pots. Cutworms can sever young spring shoots at the soil line. Mint's strong oils repel most other pests on their own.

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What does the damage look like?

Tap the closest match to jump straight to the fix.

Tiny pale dots and webbing

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Curled, sticky new growth tips

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Sunken dark spots in pinhole pattern

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Young shoots cut clean at soil line

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Pests, ranked by impact

Spider mites

Damage

High

Removal

Moderate

What it looks like

Almost invisible without a hand lens. Yellow-green or red-orange specks running along the underside of mint leaves and on the soft new growth at the tips of square stems. Hot dry weather and stressed indoor windowsill pots trigger fast population booms.

What the damage looks like

Tiny pale yellow dots peppering the upper leaf surface, then bronze patches that spread across whole leaves. Fine webbing strung between the leaf joints and along stem tops in heavy infestations. The harvest tastes weaker because mites drain the oil-rich leaves of moisture and flavor.

How to get rid of them

Option 1

Shower the foliage every 3 days for 2 weeks

Take the pot to the sink or hose and spray cool water on the underside of every leaf and into the leaf joints for 30 seconds. Mites can't reattach quickly when knocked off, and the rinse humidity slows survivors. Mint's vigorous square stems take a hard rinse without bruising. Repeat every 3 days for 2 weeks.

Option 2

Insecticidal soap on leaf undersides, every 5 days for 3 rounds

Use ready-to-use insecticidal soap (Safer Insect Killing Soap, ~$10).

Spray the underside of every leaf and into the leaf-stem juncture at dusk so the soap doesn't dry too fast. Wait 24 hours before harvesting sprayed leaves and rinse before eating.

Repeat every 5 days for 3 rounds. That covers the full egg-to-adult cycle.

Option 3

Move indoor pots out of dry heat

Mint is a streamside plant and hates hot dry air. Move indoor pots away from heat vents and sunny west windows in summer. A cooler humid spot stops the mite cycle without any spray. Outdoors, water deeply at the soil line each morning so leaves stay turgid through the heat of the day.

Aphids

Damage

Medium

Removal

Easy

What it looks like

Tiny pear-shaped insects 1 to 3 mm long, in shades of green, brown, or black. Cluster densely on the soft new growth at the very tips of square mint stems and along developing flower spikes. Spring and early summer are peak season as the plant pushes vigorous new runners.

What the damage looks like

New leaves curl, twist, and yellow as aphids drain sap. A sticky shiny film coats leaves below the cluster. Black sooty mold grows on the residue over a few weeks. Heavy clusters on flower spikes ruin them for harvest and reduce the second flush.

How to get rid of them

Option 1

Strong water blast every 2 to 3 days for 2 weeks

Hold a hose nozzle 12 inches from the affected stem tips and spray at high pressure. Most aphids dislodge and don't make it back. Mint's square stems and oily leaves take the rinse without damage. Repeat every 2 to 3 days for 2 weeks. Cheapest fix and works without chemicals near edible leaves.

Option 2

Pinch and harvest the worst-affected tips

Aphids cluster on the very tip of each runner. Pinch off the top 2 to 3 inches of any infested stem and drop into soapy water. This removes the bulk of the colony, encourages bushier growth, and gives you a fresh harvest. Compost only the clean stems below.

Option 3

Insecticidal soap at dusk, every 5 days for 2 rounds

Use ready-to-use insecticidal soap (Safer Insect Killing Soap, ~$10).

Spray new growth tips and flower spikes at dusk. Wait 24 hours and rinse leaves before eating.

Repeat once 5 days later to catch newly hatched aphids. Two rounds usually clear a flush.

Shield-shaped stink bug (Halyomorpha sp., Pentatomidae) on a plant

Four-lined plant bug

Damage

Medium

Removal

Moderate

What it looks like

Bright yellow-green adults 6 to 7 mm long with four black stripes running down the back. A classic mint pest. Active for a short window in late spring and early summer. Bright red wingless nymphs with black spots feed first and are easier to spot. Drop and hide fast when disturbed.

What the damage looks like

Small round sunken spots, dark brown to black, scattered across the upper leaf in a pinhole pattern. Each spot is a feeding puncture. Heavy feeding makes leaves look polka-dotted, then the spots merge and the leaf turns ragged. Looks alarming but rarely kills established mint.

How to get rid of them

Option 1

Hand-pick at dawn into soapy water

Walk the patch right after sunrise when bugs are sluggish and easier to catch.

Tap stems over a jar of soapy water. Adults and nymphs drop in and drown.

Repeat every 2 to 3 mornings for 2 weeks. The feeding window is short. Catching adults before they lay eggs ends the cycle.

Option 2

Cut the patch back hard at first damage

Mint regrows fast. Shear the patch to 4 inches at the first sign of pinhole damage in late spring. This removes feeding adults, eggs laid in stems, and damaged leaves all at once. The fresh regrowth is clean and tender for harvest.

Option 3

Pyrethrin spray at dusk for severe outbreaks

For heavy outbreaks on a young patch, spray pyrethrin (PyGanic Gardening, ~$25) at dusk. It breaks down in sunlight within hours so harvest is safe after a wait period (read the label). Spray only the affected stems. Reserve for severe damage because pyrethrin kills beneficials too.

Side view of a black cutworm caterpillar (Agrotis ipsilon)

Cutworms

Damage

Medium

Removal

Easy

What it looks like

Fat soft-bodied caterpillars 1 to 2 inches long, dull gray, brown, or greenish. Curl into a tight C when disturbed. Feed at night and hide just under the soil or mulch by day. A spring problem on young mint shoots emerging from the rhizome before the patch is dense.

What the damage looks like

Young shoots cut clean at the soil line overnight. The cut stem lies on the ground next to the stub. Once mint forms a dense mat the cutworm damage stops mattering, but a cluster of severed early shoots can reset a patch by 2 to 3 weeks.

How to get rid of them

Option 1

Hand-pick by flashlight an hour after dark

Walk the bed an hour after sunset with a flashlight on the soil surface.

Cutworms feed in the open at night. Pick by hand and drop into a jar of soapy water.

Repeat every 2 to 3 nights for a week or until cuts stop appearing.

Option 2

Cardboard collars around new shoots in spring

Cut a toilet paper tube into 2-inch rings. Push one ring into the soil around each emerging shoot, half above and half below the surface. The cutworm can't reach the stem to chew through. Remove once the patch fills in and shades the soil.

Option 3

Pull mulch back from the rhizome line

Cutworms hide under mulch by day. Pull mulch back 4 inches from the edge of the mint patch in early spring while shoots are still soft. Once shoots are 6 inches tall and woody at the base, replace the mulch to hold moisture.

Stay ahead of all of them

Four habits that defuse most mint pest pressure before it starts.

Tip and underleaf check, every Sunday

Aphids cluster on the soft new growth at runner tips and on flower spikes. Spider mites hide on leaf undersides. A weekly 30-second scan of these two zones catches colonies in their first week, when one rinse clears them.

Harvest hard and often

Mint hates being left alone. Cutting the patch back to 4 inches every 3 to 4 weeks through the season removes egg-laden leaves, breaks up pest hiding spots, and triggers fresh tender regrowth. A mint patch that's harvested aggressively almost never builds up four-lined plant bug or aphid populations.

Plant mint near brassicas and tomatoes

Mint's strong essential oils repel cabbage moths, aphids, and some flea beetles from neighboring crops. Sink the pot to the rim near brassicas instead of letting runners loose in the bed. This puts mint to work as a companion plant without letting it take over.

Water at the soil line in hot weather

Skip the overhead spray on hot afternoons. Wet leaves in a heated patch invite mint rust and dry quickly to leave the leaves stressed, which is exactly the condition spider mites need to explode. Soak the soil at the rhizome line each morning instead.

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About This Article

Kiersten Rankel M.S.

Botanical Data Lead at Greg · Plant Scientist

About the Author

Kiersten Rankel holds an M.S. in Ecology & Evolutionary Biology from Tulane University. A certified Louisiana Master Naturalist, she has over a decade of experience in science communication, with research spanning corals, cypress trees, marsh grasses, and more. At Greg, she curates species data and verifies care recommendations against botanical research.

See Kiersten Rankel's full background on LinkedIn.

Editorial Process

Pest identification and treatment guidance verified against Mentha spp. field reports from Greg's botanical database, cross-referenced with university extension sources and published horticultural research.

3+ Greg users growing this plant

USDA hardiness zones 3a–11b

Citations:
NC State Extension
Spider mite photo: Clemson University - USDA Cooperative Extension, Bugwood.org (CC BY 3.0 US)
Aphid photo: Scot Nelson (CC0)
True bug placeholder: Vengolis (CC BY-SA 4.0)
Cutworm photo: USGS Bee Inventory and Monitoring Lab (Public domain)