If you’re a nature lover, then seeing trash and debris littered in the woods or a garden, you might be someone who helps pick up trash. Even if you’re not someone who goes around with a bag to grab some trash from the ground as you go, it probably turns your stomach to see plastic bags and other junk in trees and on the side of a path.

When a person was walking through wetlands in Mildura, which is located in northwest Victoria in Australia, they came across what looked like a plastic bag stuck in the branches of a tree. It upset this nature lover because he thought someone had allowed the wind to blow a sack away from them.

But then he looked closer. And it became clear that this was not man-made waste, but a surprise born of nature. The “plastic bag” stuck in the tree was a disturbing grub nest hanging with hundreds, if not thousands, of little bugs.

The bugs in the bag are known by several names including itchy grubs, itchy caterpillar, and professional caterpillar. They use this bag shelter among the tree branches to make their transformation from grub to bag shelter moths.

When you see one of the bugs up close, they have very long hairs protruding from their grubby bodies. And if you touch it, you’ll suffer a nasty skin irritation.

The man walking through the wetlands thought the bag was a spider’s web. But when he shared the disturbing image, a person corrected him and taught him to avoid the itchy grub bag at all costs.

The image went viral when it was published to Reddit on Monday. And because the poster did not know that the nest belonged to itchy grubs, he is lucky he did not try to disturb their slumber.

A person who knew the bag for what it was left a comment: “They are common in old undisturbed forest/stands of timber and one of the things you look out for before rolling out your swag on the ground. They are that common Aboriginals have a lot of uses for what is a nasty little critter if not treated with respect.”

If someone touches these caterpillars, they can suffer an allergic reaction. They may experience itchy skin and feel irritation like rashes and other annoyances. These bugs are not deadly, but they certainly earn the “itchy” in their names.

Australians often witness the “conga lines” these caterpillars form when the wet season comes. After a lot of rain, these disturbing sights become more common. And anyone who touches the long hairs on these bugs risks facing the allergic reaction.

Itchy caterpillar conga lines can create chains up to 30 feet long. They move from tail to head as a unit. Scientists think they do this because the grubs are a social critter. So they’re sticking with their family groups.

Have you ever seen a bag of grubs hanging from a tree before? Would you have known not to touch this if you saw it?

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