Monkey Slug

What on earth is this?
September 28, 2009
While moving, my friends found this on a cardboard box that had been sitting, undisturbed in a storage room for over a year. It reacted only slightly to being touched, but when a lighter was held a few inches away from, the pustule looking things started to swell and it lifted up a few of its legs (arms?). They’ve left it alone since, except for calling me to take some pictures. In a 24 hour period it’s moved about 4 inches across the top of the box, though rarely moves at all when we’ve been looking at it. We live in southcentral Oklahoma, and the weather has been very hot for months, so the closed off storage room it was in, was very warm, and moderately humid.
curious okie
south central Oklahoma

Monkey Slug
Monkey Slug

Dear curious okie,
This is a Monkey Slug, the caterpillar of the Hag Moth, Phobetron pithecium.  It is one of the Stinging Slug Caterpillars in the family Limacodidae, and it should be handled with caution.

Photo of author


BugMan aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

1 thought on “Monkey Slug”

  1. I’m really curious to see what these things look like when they pupate. I can’t imagine a nice smooth round pupa when the larva has all of those weird tentacle-like protrusions. Can they move those “arms” by the way?


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