Larvae in a field in Kent have been confirmed as Colorado potato beetle (Leptinotarsa decemlineata).

This is the first time an outbreak of the beetle has been confirmed in the UK since 1977 – although they are endemic in large parts of Europe.

If not eradicated, these beetles are a significant threat to potato crops. The adult beetles and larvae feed on the foliage of potato and other plants in the nightshade family and can completely strip them of their leaves if they are left uncontrolled.

The Department for Environment, Food and Rural Affairs (Defra) and the Animal and Plant Health Agency (APHA) are therefore urging growers, farmers, processors and the public to be vigilant.

However, Colorado potato beetles are not a threat to human or animal health.

The APHA, which made the confirmation following laboratory diagnosis of samples taken, is working closely with the affected grower to eradicate the pest from the site in Kent.

This includes performing a 1km survey to determine whether there are further cases beyond the immediately infested area.

“We are responding swiftly through our eradication programme, involving ground surveillance to look for beetles and larvae at the outbreak site and surrounding area,” UK Chief Plant Health Officer Nicola Spence said.

“Whilst this pest does not pose a threat to human health, we encourage all growers, farmers, processors and the public to remain vigilant and report any sightings, especially in Kent.”

Colorado potato beetles are bright yellow or orange with black stripes and are usually between 8.5-11.5mm in length and 3mm in width. Its larvae are a reddish brown in colour, round and globular, and up to 15mm in length.

It was first recorded in 1811 in the US. The beetle has since spread across the US, and moved into Canada, Central America, Europe and Asia.

According to Defra and the APHA, they are occasionally imported into the UK from continental Europe as ‘hitchhikers’ on non-host plant material, such as leafy vegetables, salad leaves, fresh herbs and grain.

In the past 70 years, there have been two outbreaks of Colorado potato beetles in the UK, one in 1976 and one in 1977. Both outbreaks were eradicated shortly after detection.