An invasion of poisonous caterpillars which swept through Croydon led to a surge in call-outs for out of hours GPs.

Brown Tail Moth larvae left a trail of destruction when they blew into New Addington over the Easter bank holiday, stripping trees bare of bark and causing residents to suffer breathing problems and rashes.

The caterpillars, which can grow to 1.5 inches long, each have up to two million hairs which can break off into the air and cause severe allergic reactions.

Patient Care 24(PC24), which provides out-of-hours GP services for Croydon, Sutton, Merton and Kingston, said the number of callouts were up 12 per cent compared to the previous Easter.

A spokesman said the caterpillars were a key factor in this rise, alongside more people being out and about because of the marriage of the Duke and Duchess of Cornwall.

PC24 Elizabeth Rahim said: “While pretty much the whole of south west London was out enjoying the Easter sunshine and Royal Wedding, our staff were beavering away during an exceptionally busy time to ensure hundreds of people who needed medical care – in many cases quite urgent – received it to the quality and standard they expected.

“The particularly challenging combination of wedding celebrations, holidays and caterpillars meant we had our work cut out but I am delighted to say all our staff rose to the challenge and we hit particularly high quality targets.”

A total of 375 home visits were carried out by PC24 over the Easter weekend, and almost 1,400 people attended treatment centres in Croydon, Kingston and Sutton.

Residents said they could originally see the caterpillars moving around in cotton wool-like pods the size of grapefruit before they began blowing in windows and under front doors.

Previously only found on Britain’s south east coast, the insects have been swarming north over the last few years due to increasingly warm weather.