An Oak Processionary Caterpillar has been spotted in Battlers Green near Radlett.
Hertsmere Borough Council released a statement this month warning resident that contact with it could cause itchy rashes, eye irritations and in severe cases, breathing difficulties in people and pets.
A RadlettNews reader sent in photos of the caterpillar after seeing them and says he has contacted the appropriate authorities.
Josh Moore, who saw the caterpillar at the end of Willow Way, said: “I immediately rang the agency who deal with them. They reviewed the caterpillars and confirmed that they were indeed the dangerous species and will attempt to remove them as soon as possible.
“I was just walking home with my daughter and she was playing under the oak tree until I spotted them, and they matched the description of the Oak Processionary Caterpillar, so I thought it was important to report them.”
Residents are advised to avoid all contact with the caterpillar and their nest. They have also been spotted in Bushey Hall Golf Club.
Councillor Seamus Quilty, portfolio holder for environment at Hertsmere Borough Council, said: “During the lockdown period and warm weather our green spaces have been a welcome retreat for residents to spend time outside.
“Unfortunately, Oak Processionary Moths have been sighted in a few Hertsmere Parks, so our message is to be vigilant, especially with young children who may be exploring trees this summer.
The nets are typically dome or teardrop-shaped, ranging in size – from a ping pong ball to as large as a rucksack.
If you see any oak processionary nests or caterpillars (OPM) in a council park you should report them immediately on 020 8207 2277.
If they are on a privately owned oak tree, report them to the Forestry Commission using the Tree Alert online pest reporting form. If you cannot use Tree Alert, you may report them by telephone on 030 0067 442.