A brightly-coloured insect spotted in a garden last week piqued the interest of an inquisitive nature enthusiast who snapped a photo of the furry and colourful critter crawling across their finger.
But swiftly after posting the image online, they realised their potentially dangerous mistake as warnings such as "put him down" and "don't touch" came flooding in — despite some calling it "cute".
It appears as though the poster didn't realise at the time that they'd been touching a tussock moth caterpillar, which can cause a "severe" reaction if handled. The image was taken in New Jersey, USA, although they're commonly found in Australia and are easily recognisable by the four distinct tussocks of hair on their back.
Furry caterpillars can cause 'severe' skin reactions
Like "quite a few" hairy and spiny caterpillars, the tussock moth species can cause rashes and itching in humans. Although they are "by no mean the worst culprits", insect and plant ecologist Dr Roger Farrow told Yahoo News Australia.
"We have quite a few hairy and spiny caterpillars that can cause severe dermatitis if handled. In fact the list is quite long and includes your tussock moth caterpillars," he explained.
"In some species, there is a gland at the base of the spine that releases a toxin when the spine breaks off in the skin. This can cause a severe reaction". These include the cup moths (Doratifera species) and gum-leaf skeletoniser (Uraba lugens) among others.
In those caterpillars that do not have a toxin, like the tussock moths, "it’s the mechanical discomfort of the barbed spine entering the skin that causes a rash and itching" Dr Farrow explained — especially in sensitive areas like the inside of the wrist.
'Avoid touching any hairy caterpillar'
Dr Farrow said the "safest option is to avoid touching any hairy caterpillar". Dr. Darrell Kemp, Associate Professor of Biology at Macquarie University, agreed. "They are best enjoyed at a distance," he said. And he knows first-hand just how bad some reactions can be.
"I have experienced something like this, which amounted to an itchy/inflamed rash on my forearm lasting several days. Quite irritating," he told Yahoo, adding many hairy moth caterpillars have this effect.
Incredible colours and textures scare off predators
While pleasant to look at because of their fascinating texture and colours, the caterpillars' hairy appearance is to scare off any predators. Namely, parasitoid wasps and/or ants.
"The wasps would otherwise seek to lay their eggs in the larva, but are prevented from doing so due to the barrage of hair tufts," Dr Kemp explained. "The very colourful features of this specimen (especially the red spots) could also indicate that they are distasteful, or unpalatable to other predators such as birds".
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