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Garden pests
Colorado potato beetle
Leptinotarsa decemlineata · Insect
Also called Colorado beetle (UK and Europe).
Illustration
A yellow-and-black striped beetle whose red, black-spotted larvae strip the leaves of potatoes, tomatoes and eggplant in North America, Europe and parts of Asia. It is not found in Australia, New Zealand or the UK, where any suspected find should be reported straight away; where it is established, hand-pick it, crush the egg clusters and cover the crop.
How to spot it
- Leaves eaten into large holes, and plants stripped back to bare stems.
- Oval, shiny, domed beetles about 10 mm (⅜ in) long, cream to yellow with ten black stripes down the wing covers (five on each), and an orange head and neck shield with black spots.
- Plump, humped larvae up to 15 mm (⅝ in) long, brick-red when young and pink to orange later, with a black head and two rows of black spots along each side.
- Clusters of bright yellow-orange oval eggs on the undersides of leaves.
- Dark, sticky droppings on the leaves and stems.
Easily confused with
Ladybirds and their pupae
Ladybirds are round, not oval, and spotted rather than striped. Their orange pupae are wrinkled, fixed to a leaf and don't move, unlike the active, shiny larvae.
Rosemary beetle
Also oval and very shiny, but metallic green with purple stripes.
Wasp beetle and spotted longhorn beetle
Long, narrow beetles whose yellow and black bands run across the body, not along it.
Where it's a problem
- Worldwide: Present across most of Europe, the Americas and parts of Asia.
- Australia: Not found in Australia, and one of its most unwanted exotic pests. If you think you've found one, report it to the Exotic Plant Pest Hotline on 1800 084 881.
- New Zealand: Not found in New Zealand, where it is a notifiable organism: by law, a suspected find must be reported. Catch it if it's safe, photograph it and call MPI's exotic pest and disease hotline on 0800 80 99 66.
- United Kingdom: Not present in Great Britain or Northern Ireland, and a notifiable pest. An outbreak found in Kent in 2023, the first since the 1970s, was declared eradicated in 2025. Trap a suspect in a secure container and report it: in England and Wales to APHA on 0300 1000 313 or planthealth.info@apha.gov.uk. Scotland and Northern Ireland have their own contacts.
- North America: A major potato pest. Adults spend the winter in the soil and come out in spring as the potatoes come up, and there is often a second generation in summer.
What to do
- In Australia, New Zealand and the UK, don't let it go: catch it in a secure container if you can, photograph it and report it straight away (contacts under Where it's a problem).
- Where it is established, check plants from the time shoots come up in spring, when the adults leave the soil, and look under the leaves for egg clusters.
- Pick off adults and larvae by hand into a bucket of soapy water, and crush the egg clusters. Start early, to stop later generations.
- Cover young plants with fine row cover or insect mesh, edges secured, before any beetles appear, but only in a bed where potatoes, tomatoes or eggplant didn't grow last year: beetles coming out of the soil would be trapped underneath.
- Mulch between the plants: it makes it harder for the beetles to complete their life cycle.
- Rotate potatoes, tomatoes and eggplant to a different part of the garden each year. The beetles don't travel far in cool spring weather, so even a year without potatoes helps.
- Pull out nightshade weeds, grow early-maturing potatoes, and clean up the bed at the end of the season so fewer adults survive the winter.
In Australia, New Zealand and the UK, report it rather than treating it. Elsewhere, if you use an insecticide, choose one labelled for Colorado potato beetle and follow the label and local rules. Sources warn that in some areas the beetle resists many insecticides, so a spray may not work.
Vegetables it affects
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Sources
- Defra Plant Health Portal: Colorado beetle factsheet
- University of Minnesota Extension: Colorado potato beetle
- Farm Biosecurity: Potato pest threats
- AUSVEG: Colorado potato beetle (urban biosecurity fact sheet)
- MPI Official New Zealand Pest Register: Colorado potato beetle
- MPI: Report a pest or disease
Facts checked Wednesday 21 October 2026. General guidance only: follow your local council, agency and product label.