Mint leaf beetle
A brilliant metallic green beetle, 7–10mm and domed like a small jewel, which with its larvae eats holes in mint leaves through the summer. It is the one chewing pest of mint worth knowing, and it is separated from everything else that eats a mint leaf by simply being visible: it is large, slow, and sits on the upper surface in daylight, which slugs never do.
Caused by: Chrysolina herbacea · also called mint beetle, green beetle on mint
What brings it on
Damp ground and established mint beds, often near water. Populations are local and patchy — a bed can carry them for years while another in the same garden has none — and a vigorous mint outgrows the damage even when the beetles are numerous.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Mint beetle
- Plant Finder — Missouri Botanical Garden: Mentha — pests
Checked 2026-08-13
Usually seen: May, June, July, August, September
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Nothing worth doing in advance. Mint is confined to a container in most gardens for reasons of its own, and a contained plant is easy to inspect and easy to cut back if the beetles arrive.
source
GrowingHQ editorial positionmoderate confidence
The prevention field would otherwise imply a barrier or a treatment for a pest that does not warrant either.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
Dealing with it once it is there
- Pick the beetles and grubs off by hand — they are large and slow enough that this works — and if a bed is badly holed, cut the whole plant to the ground. Mint regrows within three weeks from the runners and the new growth comes clean, which makes cutting back both the treatment and the harvest.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Mint beetle — control
Checked 2026-08-13
What it affects
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.