Monday, September 14, 2015

Caterpillars, Caterpillars, and More Caterpillars

This time of the year belongs to the caterpillars. Right now, hundreds and hundreds of species are eating, building up stores of energy, and preparing to overwinter either in diapause (a type of hibernation), or as a chrysalis (for butterflies), or in a cocoon (for moths). Michelle Ward, a fellow undergraduate Wildlife and Conservation Biology student at Ohio University, set up a caterpillar hunting night at her house and invited several other wildlife-based undergraduates and graduate students. Her house just happens to be in the middle of a forest in northern Athens County, which made for a really awesome night. I'm going to go over a few of the more showy "cats" in this post, but there will be other caterpillar-themed posts coming!

Blinded Sphinx caterpillar
We found several sphinx moth caterpillars throughout the course of the evening. This individual is a Blinded Sphinx caterpillar, Paonias excaecatus. Notice the "horn" at the end of the abdomen, a characteristic found in many, but not all, sphinx moth caterpillars. Many sphinx moth caterpillars, such as this one, also have cryptic coloration, with most being primarily green or brown. Also notice the diagonal streaks going across the body, another common feature. In the case of the Blinded Sphinx, these streaks are brown, but we'll see another color of streaks on the next individual.

Elm Sphinx Caterpillar
This is another sphinx, specifically the Elm Sphinx, Ceratomia amyntor. Generally speaking, moths and butterflies typically feed on specific plant species versus any random plant. Sometimes this is taken to the extreme, where a certain Lepidopteran (moths and butterflies) species will only feed on one specific species of plant and nothing else. Most other Lepidopterans have a small group of plant species they will feed on, and the Elm Sphinx falls into this category. As the name implies, it does indeed feed on elm trees, but they will also feed on cherries, basswoods, and birches. Take note of the four horn-like projections near the head, a diagnostic characteristic for this species. The Elm Sphinx cat also has a horn at the end of its abdomen, along with the diagonal streaking across the body (with a whitish-cream coloration).

Apatelodes torrefacta
One of the most abundant caterpillars of the night was the Spotted Apatelodes, Apatelodes torrefacta. This picture doesn't do it justice, but these are pretty large caterpillars, with many we saw reaching lengths of 3-3.5 inches. A fuzzy little caterpillar, these can come in two different colors. All the ones we saw were the yellow individuals, but this species can also come in white.

Snowberry Clearwing Caterpillar
The caterpillars we found ranged in sizes from monstrously large (as you'll see) to very tiny. These smaller ones are hard to find by flashlight alone while bumbling around a forest at night; this is when a UV flashlight comes in handy. A UV flashlight simply emits light in the ultraviolet wavelength. This is incredibly useful for people looking for caterpillars because many (but not all) caterpillars will actually fluoresce. Essentially, ultraviolet light will be absorbed by the exoskeleton of certain species, and the exoskeleton will re-emit that light as visible light, resulting in glowing caterpillars among the dark forest (you can only do this in the dark of night). This makes finding many caterpillars much easier, especially for the small ones such as this Snowberry Clearwing, Hemaris diffinis. This is one of the hummingbird moth species, and I've previously covered his cousin, the Hummingbird Clearwing, here.  

Silver-Spotted Skipper Caterpillar
So far, all of the species I've covered have been moths. This, on the other hand, is a butterfly. It also happens to be one of the most common butterfly species in Ohio. This is the Silver-Spotted Skipper, Epargyreus clarus. Although the adults are small, the caterpillars are not. This one was around 2 inches long, and quite chubby. One of the stand-out features of this caterpillar are the two orange dots on the head. These are presumably mimicking eyes in an attempt to dissuade predators. The real eyes are too small to see in this photo. 

Hickory Horned Devil
The find of the night was this monstrous creature, the Hickory Horned Devil, Citheronia regalis. This species is also called the Regal Moth and Royal Walnut Moth, especially when referring to an adult. The common name Hickory Horned Devil is mostly used when talking about the caterpillar stage. This incredible caterpillar was humongous; it was easily 5-6 inches long. This magnificent creature is going to get a post all his own, so stay tuned! Update: Here is my post on the Hickory Horned Devil!

From left to right: Yours truly, Olivia Brooks, Brandan Gray, Michelle Ward, Cassie Thompson, Alayna Tokash, and Jake Schoen. Not pictured is Vincent Farallo.
The night was a smashing success, and not only in regard to caterpillars. We also had a Ring-Necked Snake, a few Red-Backed Salamanders who were out and about walking around, and a surprise Marbled Salamander (who are migrating right now). Our group is pictured above (I'm on the far left).

As I previously mentioned, I'm planning a few other caterpillar posts in the upcoming days. I'm definitely going to have one on the Hickory Horned Devil (Update: Post on the Hickory Horned Devil), and I am trying to find enough species for a post on some of the slug caterpillars of Ohio, which are the coolest caterpillars in my opinion. If you like caterpillars, stay tuned! Thanks for reading!

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