Colorado potato beetle
The most damaging potato pest in Poland. Adults and larvae of Leptinotarsa decemlineata eat the foliage — in a mass outbreak they strip plants bare in a few days and tuber yield can halve.
Symptom photos
Symptoms
- Beetles with 10 black stripes on yellow wing cases
- Orange-red larvae with two rows of black dots
- Yellow-orange egg batches on the underside of leaves
- Eaten leaves, in extreme cases only stalks and stems left
- Black larval droppings on what is left of the blades
What it does to the crop
- Loss of leaf area and small tubers
- Yield down by up to 50% if the foliage goes during flowering
- Young plants dying under heavy feeding
- Two generations a season and a fast-rebuilding population
What encourages it
- Temperature above 15°C and warm, dry weather from May
- Potatoes or other nightshades grown in succession
- Beetles overwintering in the soil of last year's plot
- Leaf undersides not checked during egg-laying
Prevention
- Inspect plants every 3-4 days and wipe off egg batches
- Pick beetles and larvae off by hand on a small plot
- Rotate crops and keep distance from last year's plot
- Deep autumn cultivation to destroy overwintering beetles
- Plant earlier and use early varieties to dodge peak feeding
⚠️ Before you reach for a spray
This atlas is informational and still growing — different diseases can look almost identical. Confirm the diagnosis and read the product label before applying any plant protection product. If you are unsure, ask your local extension or advisory service.
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