Caterpillars are the unsung heroes of nature

 

An elm sphinx caterpillar (Ceratomia amyntor) strikes a "defensive" pose/Jim McCormac

Columbus Dispatch

August 30, 2026

NATURE

Jim McCormac

Something like one-third of Americans believe in reincarnation. Apparently, these wishful thinkers mostly want to come back as animals. Golden retrievers, eagles and tortoises are popular rebirths.

I have a word of advice for the reincarnation crowd: caterpillars. As in, don’t come back as one. I’ll circle back to that in a bit.

Caterpillars are the larvae of butterflies and moths, mostly the latter. Worldwide, moth species outnumber butterflies by a factor of eight. In Ohio, the imbalance is far greater, with moths probably bettering butterflies by a factor of nearly 20.

As George Carlin once said, “The caterpillar does all the work, but the butterfly gets all the credit.” How true that is. People marvel over showy butterflies and cool moths that come to their lights, but many probably don’t even know that they were once a caterpillar.

That’s a shame, as caterpillars are a huge part of our natural world. Believe it or not, they are, by biomass, often the largest group of herbivores in many places. Not white-tailed deer. Take all the deer in 71,000-acre Shawnee State Forest in southern Ohio. I don’t know how many deer that would be, but they’d make an enormous pile.

The bizarre red-washed prominent caterpillar (Oligocentria semirufescens) is a leaf-edge mimic/Jim McCormac

Now somehow harvest every single caterpillar in Shawnee in early September, when their numbers are the greatest. The caterpillar pile would dwarf the deer heap.

Virtually all caterpillars are vegan, and their fare is wild plants. Plants do not want to be eaten, we must assume, and they practice better living through chemistry to battle the ravenous caterpillars.

Plants produce myriad compounds that evolved to ward off caterpillar consumption. Caterpillars continually evolve resistance to these phytocompounds, and some species always crack the chemical code and can eat even the most toxic species.

The best-known local example of this is the monarch butterfly. It only eats members of the milkweed family, and these plants are rich in toxic cardiac glycosides. Excepting the butterfly, milkweed tussock moths and a handful of other moth caterpillars, little can eat these poisonous plants.

Saddled prominent caterpillars (Heterocampa guttivitta) are larval art/Jim McCormac

Milkweeds’ opposite is the white oak (Quercus alba). Over 500 species of caterpillars use it as a host plant, nearly all of them moths. Possibly the oldest plant in the state is the famous white oak in Old Logan Cemetery in Hocking County. That behemoth has spawned millions of caterpillars over its long life.

Humans are beneficiaries of this age-old evolutionary warfare between plants and caterpillars. Many anti-caterpillar phytochemicals are used in foodstuff, medicines, spices, dyes, rubber and much more.

Perhaps the greatest ecological role of caterpillars is transforming plant tissue into an edible form of protein that can be eaten by birds. Few birds eat leaves, but rare indeed would be the bird that would reject a caterpillar. They are nature’s hot dogs; little steaks on legs. They are the major component of many songbirds’ diets. Were caterpillars to vanish, so would orioles, tanagers, vireos, warblers and many others. Forests would fall silent.

Even vegetarian songbirds such as sparrows harvest caterpillars when they have chicks in the nest. Nestlings need rich protein sources to fuel their growth, and caterpillars fit the bill.

It isn’t just birds that hunt caterpillars. A favorite of black bears is one of the most reviled caterpillars by humans. Eastern tent caterpillars make large silken nests in black cherry trees in late spring. Many people despise them, and I have heard of ecological ignoramuses using blow torches to burn them from the trees. But black bears love them, and a bruin can eat up to 25,000 (22 pounds!) tent caterpillars a day.

There are perhaps 100 black bears in Ohio, and their numbers are increasing. This is a wonderful case of a once-vanquished mammal coming back, and caterpillars are helping to fuel their recovery.

Predation rates of caterpillars are astronomical (take note, reincarnationists). Probably only a few percent survive the predatorial gauntlet. Thus, moths and butterflies carpet-bomb reproduce by laying hundreds of eggs to ensure some survive to adulthood. Caterpillars are a base layer of food webs.

Caterpillars are masters of disguise and are incredibly adept at hiding. Furthermore, most species are nocturnal and active when most birds are not. Special tactics must be employed to find them. Caterpillar-hunters must venture into the dark forest and employ special blacklight flashlights. Many caterpillar species fluoresce brightly under ultraviolet light, greatly upping the odds of finding them. Some groups, such as sphinx moth caterpillars, glow so brightly that they appear to be plugged into a light socket.

Moth and butterfly larvae are tubular objets d'art and make fascinating photographic subjects. Hunting them and trying to portray their amazing artistry with a camera becomes addictive.

On Aug. 22, Shauna and I traveled to the backwoods of Jackson County to the 195-acre spread of our friends Julie and Rod Sheets. It was larval madness, and it seemed that every tree produced interesting subjects. Some of my captures from that nocturnal safari accompany this article.

To learn more about caterpillars, visit The Caterpillar Lab at thecaterpillarlab.org.

Naturalist Jim McCormac writes a column for The Dispatch on the first and third Sundays of the month. He also writes about nature at jimmccormac.blogspot.com.

The smaller parasa caterpillar (Parasa chloris) suggests a hippopotamus/Jim McCormac

A fabulous evening of caterpillaring

 

As always, click the photo to enlarge

An American Dagger (Acronicta americana) moth caterpillar noshes on the leaf of a Red Maple (Acer rubrum). We saw many of this species on this evening. American Daggers are polyphagous - they can eat the foliage of scores of plants. It is often one of the most common caterpillars we find on night prowls, if not the most common.

Last Saturday, August 22, Shauna and I headed southeast and into the hills of Jackson County. This is one of the most biodiverse counties in Ohio. We headed towards the property of Julie and Rod Sheets, friends that we met last spring during a flying squirrel research project that took place on their 195 acres. After traipsing over some nice swaths of the place during the squirrel project, I probably commented to Rod and Julie that "this place would be great for moths/caterpillars!" 

And there we were, returning at a peak time for lepidopteran subjects. While the mothing (if you're new to the term, "mothing" entails luring moths to an illuminated sheet) was a bit tepid, their larvae were quite robust and put on a great show. And some of these caterpillars are featured here.

Usually, between keeping an eye on the sheet for moths, we search nearby habitats for caterpillars. Our efforts are greatly aided by the use of blacklight flashlights ("UV BEAST" is a good brand). A great many caterpillar species fluoresce, often quite brightly, when caught in our purple beams. 

We didn't make it 20 feet from the sheet when Shauna shouted "look!" She had found not one, or two, but three!! Saddleback Caterpillars under a single redbud leaf. That fortuitous find proved to be a good omen, and we went on to find many more interesting larvae. Some photos of those follow.

A Banded Tussock Moth caterpillar (Halysidota tessellaris). This species vies with the American Dagger for the most frequently found cat. It, too, is polyphagous and can seemingly ingest anything. Such a catholic diet is not the norm for caterpillars. Far more caterpillars are specialists, eating only one family of plants, one genus, or even only a single species. Nonnative plants species do very little for caterpillars. Most can't eat them, due to long-evolved chemical compatibly with only their host plant(s).

We were pleased indeed to discover this fully grown Elm Sphinx Moth caterpillar (Ceratomia amyntor). This species is a hyper-specialist, eating only plants in the elm family, and only those in the genus Ulmus. The Sheets' property has plenty of American Elm (Ulmus americana) and Red Elm (U. rubra), and I was watching for one of these four-horned beauties. In my photo, it is rearing up in what appears to be a defensive posture that they often adopt when disturbed. 

If you noticed how leaf-like the Elm Sphinx cat is in the first shot, this one should reinforce that. The larva clearly mimics the elm leaf both in color and venation. I couldn't get this one to cooperate very well, as I was trying to pose it so that its raised white stripe that runs the length of its back was aligned perfectly with the leaf's central midrib. That's how they often rest when not feeding. The caterpillar's angled lateral lines then mesh perfectly with those of the leaves.

This is a Hackberry Dagger Moth caterpillar (Acronicta rubricoma) and it wasn't even on my radar. I'd never before photographed one and can't remember even seeing one. But I don't keep a list and there are LOTS of bugs and I can't remember them all.

Anway, the aptly named Hackberry Dagger is a hackberry feeder, and hackberry is also in the elm family. It also apparently eats elm, and weirdly, it is claimed that they will also consume sumac (unrelated family). I checked Ohio records in iNaturalist, and while the species has been recorded statewide, records were rather sparse and scattered and probably the vast majority of those records were of the adult moth phase rather than caterpillars.

I've long wondered about the vertical stratification of caterpillars feeding in trees, and whether there might be a suite of species that typically feeds in the crowns. It may be that there are certain cats that are hard to clap eyes on because they are usually high overhead and out of sight. Maybe the Hackberry Dagger is one of them. There, now 43 people will tell me about all of the Hackberry Daggers that they encounter :-)

An Io Moth caterpillar (Automeris io) makes an artistic stinging edge to a dogwood leaf. Those envenomating spines will make you rue touching one. I did so accidentally once, and it was akin to an especially potent Wood Nettle (Laportea canadensis), the most painful of our nettles. The Io cat is also polyphagous and probably the most commonly encountered silkmoth caterpillar, at least for me.

We did well with the always interesting slug moth caterpillars such as this Jewel-tailed Slug (Packardia geminata). Some species resemble snails, as this one does. Its head, on the right, is extended; it's frequently not visible.

The reason for the insertion of "slug" into the name of this group is due to their curious method of locomotion. Instead of a series of central prolegs, slugs have sets of paired suckers. They glide along on a thin film of silk, much like a slug moves.

Here's the trio of Saddleback Caterpillar Moth caterpillars (Acharea stimulea) that started off the night prowl. In the words of entomologist and caterpillar expert Dr. David Wagner, slug caterpillars are "more fantasy than reality".

This species has one of the most painful stings of any North American caterpillar, so look but don't touch. Those columnlike extensions are bristling with envenomating spines. There is a venom sac at the base of the spine, and when triggered it blasts the hot sauce into the interloper like an injection from a hypodermic syringe. While stings will probably hurt anyone that experiences it, some people can react very badly.

A Saddleback cat resembles a little tubular chestnut horse draped with a lime-green horse blanket. Unfortunately for the larva in my photo, it is a walking dead caterpillar. Near the top left of its body, where there is a thin band of green, it looks like someone put a tiny cigarette out. That's either an air exchange hole for the larva of a tachinid fly, or its exit hole. Either way, the caterpillar won't survive the internal ravages of the fly maggot. Such parasitoidism is very common in the caterpillar world.

Yet another slug moth caterpillar and it isn't the last (almost, though). This is a White Flannel Moth (Norape ovina), and it is an outrageous insect. Check out those uber-long setae, and the showy jewel-like studding on the body. Those "jewels" are also studded with envenomating spines, and the sting is said to be quite painful (I could talk no one into getting stung so that we could learn about this).

Finally, insofar as the slugs go, here is our grand finale: the utterly bizarre Lesser Parasa Moth (Parasa chloris). Dr. Seuss himself couldn't make this thing up. To me, from certain angles, they look like hippopotami. This parasa is actively feeding and its head is tucked out of sight.

This is a White-dotted Prominent (Nadata gibbosa) and it's primarily an oak feeder. This one is apparently preparing a temporary bivouac by spinning a thick layer of silk. As the silk dries, the leaf will fold over the cat, concealing it. White-dotted Prominents are pretty common but always interesting. When agitated, they can perform an amazing act that suggests snake mimicry. I show a photo of one so engaged and describe that behavior RIGHT HERE.

Saddled Prominent Moth caterpillars (Cecrita guttivata) may be common, but they are quite showy. When one presents itself as nicely as this one did, I find it impossible to resist making photos.

Caterpillars grow through phases termed instars, and each instar stage is separated by a molt. Most of our larger species go through five instars excepting the slug caterpillars which typical have seven or even nine instars.

This is a Sycamore Tussock Moth caterpillar (Halysidota harrissii) and it is fairly young in its growth, probably in its third instar. At this stage, it eats holes from the centers of leaves of its host plant. And that host plant is the Sycamore (Platanus occidentalis). Nothing else will do for this extreme specialist.

Lastly, a fine pair of leaf-edge mimics. This one is the Checker-fringed Prominent caterpillar (Schizura ipomoea). We caught this one in transit, but when ensconced along the edge of a leaf dappled with browning necrotic tissue, the green and brown caterpillar can be quite hard to spot. The jagged back extensions provide further disruptive camouflage.

This one may one-up the previous species in the leaf camouflage department. It is a Red-washed Prominent caterpillar (Oligocentria semirufescens). From any distance, the cat - which usually hangs out on a leaf's edge - can be remarkably difficult to see, as it so greatly resembles senescent browning leaf tissue. 

Major thanks to Julie and Rod for inviting us over to explore, and for all of their conservation efforts which include many fine cats.

Blue-headed Vireo nests

 

A Blue-headed Vireo (Vireo solitarius) with a piece of redtop grass (Tridens flavus). He or she - males help with nest construction, but the sexes look very similar - was constructing a nest nearby. This was in the Monongahela National Forest in West Virginia. I made this image on April 30, 2017.

I gave a talk entitled Natural Ohio: Through the Lens for the Ohio Wildlife Center last Thursday night. We ranged through some of Ohio's best remaining natural areas, and the flora and fauna that make them special. It was a good chance to dust off lots of images from the past, such as the two vireo shots presented here.

I made this shot WAY back when, on May 1, 2011. A pair of Blue-headed Vireos were constructing this nest deep in Shawnee State Forest, in Scioto County, Ohio.

Vireo nests are works of art. I don't think many humans could craft such a fine nest, even with two hands and ten fingers. How these birds do it with their bill, and some assistance from their feet and body, is amazing. The nest is usually located at the fork of two slender twigs, but fairly low in the host tree. They are tough/impossible for many predators to reach, such as Black Ratsnakes (Pantherophis alleghaniensis). 

Yes, I know the snake's name has been changed - so many times it's tough to keep track of. iNaturalist is now calling it the Central Ratsnake. Prior to that, it was the equally stupidly named Gray Ratsnake. C'mon, herpetologists, get your act together. I'd suggest re-renaming it back to Black Ratsnake - the name that it seems most people know and love and persist in using. A nomenclatural rebellion against a particularly dumb series of name changes - an uprisal by the masses that should be listened to.

Anyway, the vireo's artistic cup is cleverly crafted from a variety of grasses and various forbs, and lined with soft plant down and other felty botanical material. Not a bad place for a baby vireo to grow up, and we need all of the baby vireos that we can get.

Upcoming presentation: Natural Ohio: Through the Lens

Sorry for the late notice on this one, but times have been busy and I let it slip. Anyway, this Thursday (August 20) I'll be giving a pictorial lecture about the very best places that remain in the Buckeye State. It'll feature flora and fauna great and small, and sites that are well-known and obscure.

It's for the Ohio Wildlife Center, and it'll take place at their beautiful facility which is not far from the Columbus Zoo in Delaware County. Registration is required, and you can do that at their website: Beautiful Ohio Lecture Series- Jim McCormac - Ohio Wildlife Center

More details, along with registration info, is at the website. Doors open at 6:30 and the talk will commence at 7 pm. Hope to see you there!

As always, click the photo to enlarge

A Sedge Wren (Cistothorus platensis) chatters his mechanical song from the summit of a big bluestem grass in Huffman Prairie. The presentation will feature many such images, covering a wide range of biodiversity.

Frosted Whiteface

 

As always, click the image to enlarge

A male Frosted Whiteface (Leucorrhinia frigida) in repose. On a recent July trip to Michigan's northern limits - the Keweenaw (key-wuh-na) Peninsula, Copper Harbor and vicinity - we saw many northern species that reach their southern limits in northern Ohio. This beautiful dragonfly was one of them, and it was very common in that state up north. So were other northern dragons including the Chalk-fronted Corporal (Ladona julia), which was often in association with the whiteface. Both of these dragonflies are listed as endangered in Ohio, and they occur very sparingly in a few of our northernmost counties.

It isn't hard to see how the Frosted Whiteface got its name. But the name is derived from the appearance of the male, as is so often the case with various faunal species. Females are often showier, though, at least in my estimation, and we shall have a look at a female Frosted Whiteface to see if that might be the case in this species.

Here she is, and she's a showstopper. Look at those gorgeous brown eyes, and black and lemon body. This trip was a wonderful opportunity to become more familiar with these northern dragons, which were everywhere. In Ohio, the odonatologist must make special efforts to clap eyes on a Frosted Whiteface, and he/she will not see very many.

I suspect that this species and its northern brethren that are barely hanging on in Ohio will probably vanish before long, as their ranges shift northward. There is abundant evidence of climate-caused distributional shifts in many insect species, both northern species retreating northward, and southern species rapidly advancing northward. Such range expansions/contractions have always occurred, as climates have always changed. But what we are seeing now seems accelerated and is surely induced by human-caused global warming.

Someday I will try to make time to share more examples of this.

Bristly Sarsaparilla

 

As always, click the photo to enlarge

On our recent trip to northern Michigan, we visited an amazing site known as Wetmore Pond. It's a spectacular natural area near Marquette, in the Upper Peninsula. A fairly short hike takes one back to the wetlands, which is a glacial kettle lake ringed with a wonderful fen. The hike passes through some interesting upland habitats such as the rock outcrops pictured above that overlook the fen.

And who could not notice the showy plant eking out a living in the rocky crevasses? I was quite pleased to see this one, especially in full flower. It is Bristly Sarsaparilla (Aralia hispida), a plant that I had never seen in flower.

The wetlands below, sarsaparilla above. What an incredible site to botanize and anyone with an interest in plants who finds themselves near Marquette would do well to visit Wetmore Pond.

The sarsaparilla is a northern plant, most frequent in a wide east-west belt ranging from about Winnipeg in Manitoba to the east coast, and from the Great Lakes north to the latitude of James Bay. It ranges south sparingly, primarily in the Appalachian Mountains but also in the interior to extreme northern Ohio.

However, Bristly Sarsaparilla has disappeared from some of its southernmost haunts, including Ohio. It has been collected from eight counties in extreme north-central and northeast Ohio but is now known from but one Geauga County locale. I know the Geauga County site, and it is ecologically quite similar to the Michigan locality where my observations were made.

While the flowers and inflorescences strongly suggest a parsley family member (Apiaceae), sarsaparilla belongs to a closely related group, the ginseng family (Araliaceae). 

There is absolutely no question that many southern species are rapidly expanding northward, and perhaps even more are retreating northward from their southern limits. We have lost a number of plant species that barely nipped into Ohio from the north, such as the protagonist of this blog. Long-term natural shifts in mean temperatures have always occurred and have always influenced the migration of plants.

The million-dollar question is how much human alterations and the resultant climate shifts are accelerating plant (and animal) movements. And I wonder how long the sole remaining Bristly Sarsaparilla population in Ohio will survive.

Mothing, along with a talk! Scioto Gardens, August 15

 

A male Polyphemus Moth (Antheraea polyphemus) presents an interesting visage. Big silkmoths such as this are always a hit at the sheets.

Chelsea Gottfried and I will be leading a mothing night on Saturday, August 15th. It'll commence around 8:30 pm, with Chelsea giving a brief program on moths and their importance. We'll have already set up the sheets and lights, and after the talk, we'll head out to see who is coming to visit. We'll stay until at least midnight, but participants are free to come and go as they wish.

The venue, once again, is Scioto Gardens Native Plant Nursery in Delaware County, at 2870 Curve Road. The mothing here is always interesting and can be spectacular. As you might imagine, the grounds are full of all manner of native flora so there are lots of potential host plants.

We'll also use blacklight flashlights to search for caterpillars. "Caterpillaring" is just as fun as the mothing!

One must register for this event with Scioto Gardens, and HERE IS THE LINK to do just that.

Hope to see you there!

The stunning caterpillar of the Io Moth (Automeris io). I'd be surprised if one of these doesn't turn up.