Introducing Leah Conway with an Assortment of Ohio’s Oddest Caterpillars.

To some, Ohio may not seem like a particularly exciting state. We’ve got the Buckeyes, and maybe we go down to Hocking Hills once a year -and don’t forget the Hell is Real sign on 71- but is that it? On the contrary, when it comes to wildlife, Ohio’s got some seriously cool characters. 

As the shallowest and warmest, Lake Erie is the most ecologically productive of the Great Lakes, boasting the greatest number of fish species present in any Great Lake. In spring, millions of migrating birds, including brightly colored and charismatic warblers of all sorts, stopover to rest and refuel on their northerly migration at Magee Marsh and other nearby locales along the lake. 

At the opposite end of the state, along the Kentucky border, we have two species of endangered salamanders, the cryptically camouflaged Green Salamander and the pumpkin-orange colored Cave Salamander, and spread out over the rest of the state, 22 other species of salamander. Slowly, black bear and bobcat are repopulating the eastern forested parts of Ohio, and if you’re into spring ephemeral wildflowers, there’s no better preserve system in the state to see them in than the Arc of Appalachia. 

But, it isn’t just the larger fauna that deserve notice and appreciation, and you don’t necessarily have to travel to all corners of the state to see some of Ohio’s most interesting critters. In fact, some may be living in your own backyard. We’re talking, of course, about caterpillars. 

Caterpillars, the larval forms of butterflies and moths, come in all shapes, sizes, and colors. Even among individual species, there can be different color forms and pattern varieties that can stump even the most hardcore entomologist. But don’t let the incredible diversity among caterpillars scare you away from learning more about them - follow along, or should we say crawl along, to witness a selection of our weirdest and wildest. 

One of my personal favorites can be seen below, the red-washed prominent.

This member of the notodontidae family is sometimes referred to as a rhinoceros caterpillar, and it’s easy to see why. Though not entirely obvious in this image, their camouflage is meant to resemble a necrotic leaf edge, and is at times, quite convincing. This individual was feeding on American beech, but they are reported to feed on a number of other woody species, making them polyphagous. 

Caterpillar diets vary by species as well. Though oak trees support more species of lepidoptera - over 500 in the U.S. and nearly 1000 worldwide - larvae than any other plant species, not every caterpillar wants oak on the menu. Some, like the monarch butterfly, can only feed on members of the milkweed family as larvae. The cloudless sulphur caterpillar below is a specialist on senna, but what part of the plant the caterpillar consumes is, evidently, a personal choice.

Some cloudless sulphurs will eat only the leaves of senna sp, and will exhibit a lime green coloration much different than this individual, which was only feeding on the flower petals. The petals contain carotenoids that, when stockpiled, give the caterpillar its yellow appearance. 

Most species eat fresh foliage - though a few are known to consume dead leaves - but the caterpillar of the gold moth, seen below, is a seed specialist on wingstem. Perhaps this could explain why they seem to grow so quickly, as seeds contain more protein than simple plant tissue. 

Very occasionally, there is an exception to the rule that caterpillars only consume plant parts. In North America, there’s one butterfly species that flips the script and feeds entirely on another insect species. Aptly named, the harvester butterfly caterpillar is an aphid predator, and a very efficient one at that. 

It, like its aphid prey, is fuzzy and white, blending in well with the aphid colony it haunts, which may, at times, be guarded by ants who enjoy the aphids’ sugary secretion, honeydew. However, when the harvester caterpillar first hatches from its egg, it’s smaller than the aphids it must consume, so in order to sate its bloodlust, it has to be creative; like all caterpillars, harvesters can produce silk, and will use silk threads to restrain the unlucky aphid while it is eaten alive. 

The Appalachian azure caterpillar is also tangled up in a relationship with ants and honeydew, except in this case, it’s the caterpillar producing the honeydew. 

The ants tend the caterpillars, fending off any would-be predators they can, even abandoning the rest of their ant colony, and in return, the caterpillars supply them with the nutritious and sweet-tasting honeydew. 

The caterpillars themselves feed on black cohosh, but specifically, the tender insides of unopened floral buds. Only when these buds have been exhausted will the caterpillars consider feeding on other parts of the plant, such as leaves. 

While we’re talking about food, we ought to mention there’s a caterpillar out there that plays with its food. The camouflaged looper, below, is the only caterpillar in North American to use external objects for camouflage.

While feeding, the caterpillar will use its sticky saliva to adorn itself with pieces of its host plant to disguise itself from predators such as birds, which are one of, if not the, biggest caterpillar predator out there - in particular during spring when parent birds need to supply their hungry offspring with protein-rich food. It will even change outfits as it moves around the plant, or onto another plant altogether, by replacing old pieces with new. 

In most cases, a caterpillar’s first meal is actually its own eggshell, or chorion, but as it grows, much like a snake, its skin doesn’t grow with it, so it must shed, as this button slug sp caterpillar. is in the process of doing. 

Much unlike a snake, however, after molting, the caterpillar will turn around and consume its old skin. This supplies them with nutrients while also helping to remove any physical evidence of their presence that predators such as parasitic wasps and tachinid flies might notice. 

Birds, parasitoid wasps, and tachinid flies constitute some of the greatest threats to caterpillars  and are the reason sometimes as few as one percent will reach adulthood. Tachinid flies and parasitoid wasps such as ichnuemon wasps will lay their eggs on caterpillars, and when the fly or wasp larvae hatch, they will promptly burrow inside the caterpillar and eat it from the inside out in order of least to most important organs to prolong its life as their host. In the case of tachinid flies, once they’ve finished eating, they will then burrow back outside the host, emerging as maggots. The parasitoid wasps will do the same, but then spin a cocoon atop the caterpillar, inside of which they will finish their development and emerge as adult wasps.

If a caterpillar such as the Virginia creeper sphinx above is found with cocoons, it is doomed. Often, it will climb to the end of a piece of foliage and remain mostly motionless until dying a few hours or days later, never to become an adult butterfly or moth. 

This fawn sphinx above appears healthy, but may have parasitic larvae inside that have yet to reveal themselves. Only time will tell.

To increase their odds of survival, some caterpillars have developed defensive structures like urticating hairs or stinging spines. Most members of the slug moth family have stinging spines that, when touched, may produce the same effect as a bee sting, varying in intensity based on personal sensitivity and sometimes requiring hospitalization. The slug moths have received their moniker based on another anatomical adaptation: their prolegs have been modified into a slimy belly pad on which they glide across the surface of leaves just as slugs do. However, this makes them a little slower than other caterpillars, and makes running from danger more difficult, so enter stinging spines. The four slug moth caterpillars below all possess the ability to envenomate. 

Saddleback

Crowned slug

Spiny oak slug

Monkey slug

The slug moth larvae are a strange-looking lot. With their heads recessed, protected under their thorax, only occasionally do you glimpse a face that will inform you yes, I am a caterpillar.

Above: Skiff moth with head exposed and belly pad visible. Below: yellow-shouldered slug in typical head concealed fashion.

Slug moths aren’t the only caterpillars with spines. Cecropia moth, IO, and royal moth caterpillars - all members of the giant silk moth group - bear spines, though only one can sting. 

As caterpillars, regal moths (also known as royal walnut moths) are referred to as hickory horned devils. They are the largest caterpillars in the world, reaching six inches and looking much like metallic green hotdogs with horns. They’re most often seen roaming the forest floor in early fall while searching for a winter pupation site. Should you find one, count yourself lucky, as they’re not often encountered, and don’t be scared - despite their threatening appearance, this caterpillar’s horns are harmless and entirely for show, just like their cousin, the cecropia moth, below.

Only the IO (pronounced “eye-oh”), below, can sting.

It only seems fair that these caterpillars are a little prickly; as adult moths, they rarely live beyond a single week. They don’t possess functioning mouthparts and thus cannot feed, so their only purpose is to find a mate and lay the next generation before their fat reserves run out. 

This bright yellow spotted apatedlodes is covered in hairs, but they lack the ability to cause a skin reaction - and lucky for us! Close examination reveals bright red booties on their prolegs.

There are other forms of defense besides stinging spines and irritating hairs in caterpillars. Some, like these red-humped caterpillars, are gregarious, meaning they stick together and attempt to make use of the “safety in numbers” principle. They’re also brightly colored and starkly patterned to warn of toxicity. 

The same can be said for turbulent phosphilas (below), which are known to remain together for most of their lives as caterpillars.

Black swallowtails, which feed on non-toxic plants like parsley, dill, and fennel, also use this defense, known as aposomatic coloration, though they’re only feigning to be unpalatable.

Others will attempt to blend in with the foliage on which they feed. The wavy-lined prominent below wears green, brown, and white in a mottled pattern often seen on leaves with some sort of damage. It also bears antler-like projections behind its head!

When looking at this spicebush swallowtail in the beginning stages of forming its chrysalis (below), you might wonder how such a bright orange coloration would be helpful when attempting to camouflage. 

After all, for much of its life as a caterpillar, the spicebush swallowtail is green and disappears into the foliage of its host plants very well (it will also fold a leaf around itself, stitched together with silk, to take shelter when not feeding). But when ready to pupate, caterpillars will usually leave their host plant, sometimes burrowing into the soil or finding a sturdy, discrete place to base their cocoon or chrysalis. Since most of the leaf litter on the forest floor consists of leaves varying in shades of brown, yellow, and orange, the caterpillar adapts by changing its color to match, so that while it is crawling around in search of a pupation site, it doesn’t stand out as the only green thing moving. 

It’s chrysalis, too, blends in shockingly well among old leaves.

Well, there you have it. You’ve become acquainted with twenty-four out of the 3000+ species of lepidoptera in Ohio. We hope this snapshot into the ecology of these select few has fostered a new and lasting appreciation for one of our most important and imperiled groups of animals on the planet. Insect populations as a whole across the globe have been steadily declining over the past several decades as a result of habitat loss and pesticide use. If you want to help your local population, planting host plants for caterpillars to feed on and nectar plants for adults to feed on is just about the most impactful thing an individual can do.  

Leah Conway is an Ohio naturalist and wildlife photographer. She has been photographing local Ohio flora and fauna for the past ten years, with an emphasis on salamanders, wildflowers, and lepidoptera – butterflies and moths. During this time, she also acquired a Bachelor of Fine Art in Photography from Columbus College of Art & Design and, mostly recently, a natural resources management degree from Hocking College. She hopes to advocate and facilitate positive change for the natural world via education, inspiration, and direct participation in conservation causes.

http://leahconwayphotography.com/

Instagram: leahconwayphotography