Spiny Oak Slug – Poisonous Caterpillar

Q: I have encountered a tomato plant pest that I have not come across before. I took some shots of it with a computer microscope at 10X magnification (attached). The body of this pest is green, and it has the expected compliment of six legs underneath. The top view shows a bunch of “false” legs around the outside edge, however. I was wondering if anyone at the extension service could identify this creature, and tell me what to do about him and his friends!

A: I hope you didn’t touch the creature! It’s a stinging caterpillar known as the spiny oak slug.

The “legs” along the side exude an irritating liquid.

The best way to control them (and any other caterpillar) is to spray one of the organic “Caterpillar Killer” products containing Bacillus thuringiensis (B.t.)

Guide to Stinging Caterpillars


Young spiny oak slug (larger ones are as big as the dime pictured)

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