What Are Toxic Caterpillars? Health Warning Issued in England for Bug That Causes Vomiting, Asthma Attacks

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A group of caterpillars with long, toxic hairs are pictured in a forest in Diest, Belgium in 2007. Kris Van Exel/AFP/Getty Images

England officials are warning about an invasion of toxic caterpillars that are popping up in the south-east part of the country.

The white-haired caterpillars, which become oak processionary moths (OPM), can cause humans a number of unpleasant side effects including rashes, vomiting and asthma attacks, BBC reports.

A gardener who was unknowingly working under an oak tree, where the caterpillars are found, says she came down with severe symptoms after coming into contact with them.

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A group of caterpillars with long, toxic hairs are pictured in a forest in Diest, Belgium in 2007. Kris Van Exel/AFP/Getty Images

"My first symptom was a rash on my tummy. I was unaware of what is was and thought at first it was a heat rash," the woman, who also thought it could be shingles, told the BBC. "The rash got worse and the left side of my face became covered in this sore irritating rash. I contacted my doctor and it was confirmed I had been severely affected by OPM."

A protein, called thaumetopoein, in the caterpillars' hairs are what causes health issues for those who come into contact with them, according to the British Forestry Commission.

The Commission has advised the public not to touch the creatures. They've also advised pet owners to keep their animals away, Gloucestershire Live reports.

Officials have been spraying oak trees with an approved biopesticide with the hopes of getting rid of the moths. The outbreak of larvae were first spotted in mid-April but have been in the country since 2005 after they were accidentally transported in on plants from continental Europe, The Associated Press reports.