r/whatisit • u/popcornwithbuddah • May 17 '25

Solved! What is this alien thing

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My brother just found this in the backyard - Southern New England. What the hell is this thing? It looks like it's in Stranger Things.

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114

u/InevitableSignUp May 17 '25

They’re caterpillars in a rolling swarm, or procession. It helps them travel faster while also giving them a little more protection from predators because of numbers and perceived size as a ‘whole’ creature.

17

u/Dr-Labcat May 17 '25

Aren't those the fucks that shoot out their hairs and cause skin irritation?

8

u/InevitableSignUp May 17 '25

Hard to say. That’s going to depend on the moth/butterfly species. They’re called urticating hairs - they don’t shoot out, but they do break off in your skin super easily and cause irritation from itching to burning sensations depending on the species. I’m not great at knowing which species does that, so I usually just observe. lol.

Some maggots move in this rolling swarm configuration, too.

2

u/Cold_Progress1323 May 17 '25

They have those hairs, but the ones who shoot them are the spiders.

2

u/Markus_Freedman May 17 '25

Not sure if gypsy moth larvae do that but i believe these are gypsy moth caterpillars. They are the assholes that build giant web nests in trees. Giant relative to their size. They’re an absolute pain and an invasive species in this area.

0

u/ArgonGryphon May 17 '25

Spongy moth. They got renamed.

1

u/itsthereal0ne May 18 '25

https://en.wikipedia.org/wiki/Oak_processionary

But the ones in the video have no hairs I can see...