Potato growers across the United Kingdom are being urged to step up field surveillance following renewed warnings from the Animal and Plant Health Agency (APHA) regarding the threat posed by the Colorado beetle (Leptinotarsa decemlineata), a quarantine pest with the potential to cause serious economic damage to commercial crops.

The alert, issued on 19 May by APHA and the Department for Environment, Food and Rural Affairs (Defra), comes in the wake of confirmed sightings of larvae in a commercial potato field in Kent in 2023. While isolated outbreaks have historically been swiftly contained – including in the 1930s, 1950s, and 1970s – the agency warns that continued vigilance is essential to protect the UK’s £800 million potato industry.

“The Colorado beetle poses a significant threat to plants and the wider potato industry,” said Professor Nicola Spence, Defra’s Chief Plant Health Officer. “The public have an important role to play in helping us take swift and effective action to protect UK biosecurity.”

Adult beetles and their larvae feed voraciously on potato foliage, and can rapidly defoliate entire fields if left unchecked. Larvae are particularly destructive, growing up to 15mm in length and displaying a characteristic reddish-orange body with black spots. Adults are easily recognisable by their cream-yellow colouring with ten black stripes and an orange head.

Although not native to the UK, Colorado beetles have been repeatedly intercepted at ports and borders, often arriving as contaminants or “hitchhikers” on imported vegetables, leafy greens, grains, or even frozen produce. APHA has confirmed that import surveillance remains active, but emphasised that ground-level reporting by professional growers remains vital.

“Public vigilance was key to eradicating the beetle in the 1970s,” said APHA Interim Chief Executive Dr Jenny Stewart. “We really need farmers to step up again and report suspected sightings to protect UK crops.”

While awareness-raising efforts are currently underway at events such as the RHS Chelsea Flower Show, industry-specific efforts are also being mobilised. Sector organisations are encouraged to disseminate identification resources and train field personnel to recognise signs of infestation.

The pest does not pose a threat to human health, but its agricultural impact can be severe. In continental Europe, where the beetle is established, significant crop losses and increased pesticide applications are common. The beetle’s presence in the UK would also trigger stringent phytosanitary controls and could restrict access to export markets.

Suspected sightings in England and Wales should be reported immediately to APHA at 0300 1000 313 or via email to planthealth.info@apha.gov.uk, including photos and precise location details. In Scotland and Northern Ireland, reports should be directed to the relevant local plant health authorities.

More detailed identification materials and guidance for commercial growers can be found in the official Colorado Potato Beetle Plant Pest Factsheet provided by APHA.