Wednesday, October 1, 2014

Spiny Oak Slug

About two weeks ago I was hiking up along the Radar Hill Trail at The Ridges in Athens. I was checking trees along the path every now and again to see if I could find any cool caterpillars, as late Summer and early Fall are really great times for these Lepidoptera larvae. Lepidoptera is the order of insects that includes the moths and butterflies. As I glanced over a low oak tree, a small quarter-sized blob of colors and spikes grabbed my attention about 7 feel off the ground...

Spiny Oak Slug Euclea delphinii
Upon closer inspection, I saw this colorful "blob" was actually a Spiny Oak Slug caterpillar, Euclea delphinii. Although the word "slug" is in the name, these are not actual slugs, nor are they even closely related; slugs are molluscs and the Spiny Oak Slug is an insect. Moth species in the family Limacodidae are typically called "slug moths" because their caterpillars look very similar to slugs. Check out Jim McCormac's blog post on slug caterpillars to see their slug resemblance, as well as to see some of the simply outrageous forms these caterpillars come in.

Spiny Oak Slug
Spiny Oak Slugs come in a variety of colors ranging from green, yellow, red, and orange. Although they are called Spiny Oak Slugs, the larvae feed on a range of woody plants and not just oak trees. You can find the larvae here in Ohio typically from August to October. Many slug moths, including this one, are actually stinging caterpillars, meaning they can sting other creatures. Those spines you can see all over the caterpillar are specialized hollow setae that will inject poison into predators. With humans, most of the stings happen accidentally as a person rubs against one when hiking or touching a plant; these guys do not go out of their way to sting humans. When a person does get stung, the level of pain can vary not only with the species (as some have stronger poison than others), but can also vary depending on how reactive you are to the toxin. Generally speaking, Spiny Oak Slugs only cause mild discomfort. Still, slug caterpillars are those types of animals where you should only look and not touch.


  1. Hi I love the things that you post. I have a question... In a past post you had went hiking in pickaway co... was this a public trail... If so where is it?? Thanks

    1. Thanks!

      As for the Pickaway County trails, they were either at AW Marion State Park or Calamus Swamp Preserve, both of which are open to the public!