Black Arch Caterpillar
I found this Black Arch caterpillar while frolicking in Shenandoah National Park. I’ve read somewhere that they are rare to unusual, but they are everywhere out here! I’ve greatly appreciated your help in the past and thought you’d like to add this picture to your collection.
Shenandoah National Park, VA
We are happy our site proved helpful with your identification. It seems like the Black Arches Caterpillar, Melanchra assimilis, is correct. We did some internet research and found some information. The Butterflies and Moths of North America website indicates a very small reported range in Montana. BugGuide shows more extensive data, reporting the species from Montana, Minnesota, Maine and New Hampshire, but on the information page for the species, BugGuide indicates that it ranges to Virginia. It is also indicated that the species is “uncommon to rare, according to Charles Covell ” and later in uncredited information that ‘larvae feed on bracken, sweetfern, goldenrod, st. johnswort, alder, ash, birch, willow. Wagner lists also aster, goldenrod, mullein, raspberry, and tamarack and concludes “primarily a generalist on low-growing plants.’ ” We find it odd that the caterpillar would be rare with such an extensive list of food plants. If you say they were very numerous, perhaps the real explanation is that the populations are highly localized and may be quite plentiful where they are found. We found the previous posting on our site that you credited with providing your identification. We are very excited to see if a new feature that our web host has provided for our site works properly. Now, the five closest matching posts will appear as links with your post, which should lead our readership to other posts of the same species.