The WGNSS Nature Photography Group met on September 1, 2018 at Don Robinson State Park in Jefferson County, MO, with the goal of finding slug moth caterpillars and whatever other macro subjects of interest we could find. Overall, I think we had good fortune on this hot and muggy, late-summer day, finding quite a few interesting caterpillars. The slug moth caterpillars were a little scarce, but we did find a little something extra special – the pin-striped vermilion slug moth (Monoleuca semifascia) (Hodges # 4691). In four summers of looking for slug cats, this is the first one I have seen. It is a southern species and I assumed it would need to be found in the south-western part of our state where the open barren woodlands and savanna type environments this species prefers are more common.
This is the 14th of 15 species of slug moth caterpillars that are found in Missouri that I have been able to see and photograph. One more to go!
Slug cats can be found on virtually any species of woody plant in the state. Although oaks and hickories seem to be the preferred host plants, this animal was found on an eastern redbud (Cercis canadensis).
I hope these photos make it obvious why hunting these cats can become quite addictive.
The highly variable colors and patterns of the skiff moth are hypothesized to mimic senescent/necrotic lesions on leaf surfaces. They often have paired white spots that are thought to mimic the eggs of the tachinid fly, a parasite that enters the caterpillar after hatching. These “egg mimics” are hypothesized to work by dissuading flies that may attempt to avoid depositing eggs on victims that were previously parasitized.
These guys remind me of the tornado chasing vehicles that were on those TV shows about a decade ago.
This one was photographed on my wife, Sarah’s finger at Shaw Nature Reserve.
Finally, I was able to photograph the adult during National Moth Night this summer.
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.