Arguably the most stunning of Missouri’s slug moth caterpillars, the Stinging Rose Caterpillar can most often be found on oak and hickory saplings. However, a number of other woody species (including those in the rose family) will also be used as host plants.
This is one of the species I voluntarily allowed to sting me – it wasn’t that bad, perhaps a mild ‘stinging-nettle’ type of experience that was gone in 30 minutes or so.
The image below shows a little of the variety of color and patterns that can be found in this species, this one showing more of a yellow/orange background. Some animals can be found that are completely yellow.
The next slug to make your acquaintance is the Red-crossed Button Slug. This species is quite similar to one or two others as both larvae and adult, but given that most lists I have seen from Missouri list this one and not the others, I am pretty confident in this ID. This species lacks the stinging, protective hairs, going instead with a more camouflage approach of looking like a bit of leaf blight as it passes over leaves of oaks, hickories and quite a few other known woody, deciduous host plants.
The image above gives a glimpse into how the slugs get around – on a substance described as liquid silk. See the winding trails?
Here I caught one in the act. From what I’ve read, slugs leave distinctively shaped (indented) frass that is different from that of other caterpillars. I didn’t pause long enough to investigate.
Finally, the adult slug moth is pictured above. Slug moths are strongly attracted to lights and, from what I have read, are often some of the first species to show up when setting up a light and sheet/trap. I have a theory that this may be why I find many less slug caterpillars the closer I look near St. Louis. Although I found very similar habitats with the same composition and numbers of sapling oaks and hickories (the favored host plants), the closer I came to the city the number of slug caterpillars dropped significantly. Perhaps the city lights are sucking in the adults before they are able to reproduce? Probably a too simplistic idea, but it is a trend I noticed. It could just as well be due to fragmented habitat and overall less habitat available the closer one gets to the city.
We were quite fortunate during our first summer of hunting for “slug” caterpillars – members of the moth family Limacodidae who get their name from their absence of prolegs, which are replaced by a sucker that enables them to move quite similarly to a true slug. We (Sarah, Steve and I) were fortunate because we were able to locate and photograph ten species of slugs. I had read about these fascinating animals before, but never realized how abundant and diverse they actually were in the Missouri Ozarks. Yes, a good amount of work and patience is necessary to find them – I don’t want to tally up the hours, but it was time well spent outdoors.
I’ve decided to begin sharing these images with a species that is probably most well known of those who have heard of the slugs – the aptly named saddleback caterpillar. As can be seen in the image below, the saddleback wears a green saddle, bordered with white. Also apparent in these images are the urticating (stinging) hairs that are concentrated along fleshy nobs located at both ends of the caterpillar. These spines are found on a number, but not all of the caterpillars in this family and are capable of delivering a painful sting that is quite similar to that of the stinging nettle plant.
The image below shows the ocellus, or eyespots, which are actually on the posterior end of the animal.
Finally, the anterior end – the animal’s head is nicely hidden under a few fleshy folds that are armed with spiny protuberances.
I look forward to sharing more examples of this fascinating group of Missouri slugs in the near future.