Maroon caterpillar with yellow racing stripe – Gray Half-Spot

2022 November 20

I found this dark red, almost black caterpillar crossing our road on September 28, 2022. I had also seen one the previous day, and another the following day, so they were obviously (a) very common, and (b) on the move.

This looked familiar, so I went back through my postings and found a very similar caterpillar that I posted in 2011. It isn’t quite the same color, the previous one was not as dark. But the shape of the head is pretty much identical,

and the yellow “racing stripe” is in exactly the same place.

I had a lot of trouble identifying it last time, but eventually found out that it was the caterpillar of the Gray Half-Spot Moth, Nedra ramosula.

Since I was finding these in September, and Sam and I found the previous ones in June, it is pretty likely that they overwinter by hibernating as caterpillars, and pupate probably in late June or early July. Bugguide says that the adults “fly from April to October in Ohio”, which kind of suggests that they aren’t necessarily all the same age when they overwinter. This could account for the different color and somewhat different shape of today’s caterpillar vs. the 2011 caterpillar – this one may have had another molt to go through before it was ready to pupate.

Bugguide says that the caterpillars eat “St. John’s Wort”, which I assume probably means any plant in the family Hypericaceae. These are perennial plants that have small yellow blossoms, and I think I’ve seen them growing around the place in some quantity. You may have heard of these plants before, as they are a popular herbal remedy and are under investigation for antibiotic properties and as antidepressants. Still, they are toxic plants[1], and contain chemicals that can cause skin to blister when exposed to light, so I don’t advise using them as an herbal remedy without a certain amount of care and caution. And, as is common in these cases, I strongly suspect that the caterpillar that eats these plants is filling its body with its toxins.

I do wonder sometimes if that would be a useful way of extracting medicinal compounds from plants. Instead of fooling around making tea from the leaves, just raise caterpillars on the plants and eat the caterpillar directly[2]. Heck, a lot of them put the toxins in their skins, so we could just wait for them to molt and collect the shed skins. Or, if it turns out to be necessary to consume the whole caterpillar, they could be pickled or dried if you don’t want to eat them raw.

[1] Remember, “the dose makes the poison”. Just because a small amount of a chemical has useful properties as a drug, doesn’t mean it won’t make you sick or kill you in larger quantities.

[2] Apparently, tobacco hornworms feeding on tobacco plants don’t store the nicotine in their bodies, but instead exhale it as an insecticidal fog. So instead of smoking a cigar, one could just stuff a caterpillar in a tube and suck air past it to pull nicotine into one’s lungs. And before someone complains that that’s gross, well, at least it wouldn’t result in clouds of foul-smelling smoke.

One Response
  1. December 23, 2022

    Smoking caterpillars, eating caterpillars, I just don’t know. Sometimes the cure is worse than the disease.

    As for foul-smelling smoke, I have to say that I’ve been surprised at how good a pipe of my home-grown tobacco tastes.

    Do you ever look at the profusion of moth species and think what an overcomplicated biosphere we have? I mean, couldn’t we just get a couple of utility moths that do the same job and be done with it?

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