"Caterpillar Roundup" weekend

 

I made this iPhone snap last Saturday morning, as part of our crew puts the finishing touches on the caterpillar exhibit at the Arc of Appalachia's Forest Museum, in Highland County, Ohio, near Bainbridge.

At least ten years ago and probably longer ago than that, John Howard and I - as best that I can recall - began gathering a few larvally-minded friends to seek caterpillars in Adams and Scioto counties. We would choose somewhere around the first weekend in September, as that's when caterpillar diversity and biomass is at its peak.

Why? That's a legitimate question, with a multi-pronged answer. Foremost, caterpillars - the larval stage of butterflies and moths - are INCREDIBLY ecologically important. The lepidoptera is one of the world's largest orders of animals, and of their ranks, moths overwhelm butterflies in species diversity. In our part of the world, which is dominated by the Eastern Deciduous Forest ecosystem, moths, and to a far lesser extent, butterflies, play an incredibly important role in food webs, pollination, and the evolution of plants. Yet nearly no one is aware of this.

Two, as photographic fodder, caterpillars are hard to beat. Low-hanging fruit subjects such as deer, eagles, cranes, etc. are beat to death, in a way. There are scads of photos of such easily found fare and if you hit some popular Osprey nest or whatever, there's liable to be a crowd of people shooting the exact same thing. Nothing wrong with that, and I love shooting that stuff, too. But caterpillars, in all their magnificent photogenic glory, represent far more of a photographic wild west. I'll let the photos of various larvae in this post and following ones speak for themselves.

Three, there is the thrill of the hunt. Most caterpillars are far more active nocturnally, behavior no doubt driven by the legions of diurnal sharp-eyed birds that hunt them. A better than passing knowledge of botany is also an enormous asset, as most caterpillar species are tightly wedded to a small group of flora, sometimes only one species. So, one must venture out after nightfall, botanically interpret the habitats, and seek the larval game. We are greatly aided in this by the evolution of blacklight flashlights, which constantly get better - and less expensive. Many caterpillars fluoresce brightly under UV light, to the point that they look like they've been plugged into a light socket.

Several years ago, we switched our hunting grounds to the Arc of Appalachia properties in Highland County, which gave us access to their various lodging, and the Forest Museum as a base camp. That led to the creation of the Arc's Caterpillar Roundup, in which the public is invited in from 10am to 4pm on Saturday. Select species of larvae that our crew found the previous night is brought into the museum and exhibited on appropriate host plants. This year, nearly 150 people came and were exposed to the wonders and ecological importance of the tubular crowd. It's been wonderful, the addition of this educational element to our caterpillar-hunting safari. Visitors also have the added allure of hiking through some of the most gorgeous habitats to be found in Ohio, and some of those trails are right outside the museum.

NOTE: All caterpillars, following their public day in the sun, are released back into the wild, on appropriate host plants. No one dies, at least if we can help it (some caterpillars have been parasitized by flies or wasps, but those just provide more teachable moments). For their part, the captive cats normally just eat away, and produce prodigious quantities of frass. Frass is caterpillar poop: hard, dry little pellets of indigestible plant matter. Shauna Weyrauch had a great idea for next year: Collect all the frass pellets in a jar rather than brushing them into the waste bin. It'll be a big jar's worth, I am sure, as we normally exhibit dozens of caterpillars. And yet another teachable moment. Due to thousands upon thousands of caterpillars feeding in the woodlands, there is essentially a gentle fecal rain, and all those frass pellets go back into the soil as fertilizer.

PHOTO NOTES: My caterpillar rig is the Canon R5, Canon's 100mm f/2.8 macro lens, and that same company's MT-24EX twin lite flash system. The flashes have plastic diffusers to soften the light. I like the twin lites for their versatility, and because they have pre-lights. A half tap of the shutter button activates the soft pre-lights, which allow me to focus in complete darkness without the help of a flashlight. Settings, which I rarely deviate from, are f/16, ISO 200, and 1/200 second. The latter is the camera's flash sync speed, and it's plenty fast enough. The lens' excellent image stabilizer is activated, as I'm shooting handheld for most shots. When shooting detained livestock indoors, I sometimes deviate and do some work with no flash and even use a mini-tripod for some work. In those cases, I might go down to less than a second exposure time, as long as my subject is inert. While I am not generally a big flash fan, especially for subjects such as plants, with insects it can be very useful in creating sharper, more detailed images, especially at small apertures such as f/16. For nocturnal work such as shooting caterpillar in situ, flash is essential.

Okay, on to the rogue's gallery of caterpillars...

As always, click the image to enlarge

Two last instar Imperial Moth caterpillars (Eacles imperialis) nosh on White Pine (Pinus strobus). It was a rare opportunity to photograph both green and cinnamon forms together. Some of our people raise caterpillars and will bring livestock to ensure the public gets to see them in case we fail to find any in the wild. Mary Ann Maier brought these. The big silkmoth cats, like this species, are major crowd-pleasers. 

NOTE: "Instar" is the term for a stage of development in a caterpillar. They grow through molting, often five molts for larger species, and the stage between molts is an instar.

Another spectacular silkmoth, the Io Moth (Automeris io). I made this shot indoors, using a mini-tripod for stabilization. Settings were f/11, ISO 400, and 1/6 second exposure with no flash. The cat never budged so a ridiculously slow shutter speed was possible. Note the showy fascicles of spines on the cat. Brush them, and it feels like you rubbed up against a powerful stinging nettle. Best not to handle caterpillars with spines, especially if you don't know what they are.

A Crowned Slug (Isa textula) ensconced on an oak leaf. Small but extraordinary, the creature looks like it came off a coral reef. The slug moth caterpillars are a bizarre lot, and always a hit among caterpillar hunters.

We were indeed pleased to see, and have the opportunity to photograph, this little gem. It's the caterpillar of a butterfly, too, while the overwhelming majority of species in this series of posts are moths. John Howard had found it the preceding day and brought it back for everyone to see.

It is a Juniper Hairstreak (Callophrys gryneus), an extreme specialist. The cats, at least in our part of the world, eat only Red Cedar (Juniperus virginiana). The caterpillar is also a great example of botanical mimicry, as they match the cedar needles to a remarkable degree, both in color and form.

A larger-scale view of the hairstreak cat. They can be quite difficult to spot when ensconced deep among the needles.

This one could win a larval beauty pageant and is always high on our wish list. It is a Honey Locust Moth caterpillar (Syssphinx bicolor) and it is well named. I have only seen the caterpillars feeding on Honey Locust (Gleditsia triacanthos) although I have seen reports of it feeding on the closely allied Kentucky Coffee Tree (Gymnocladus dioicus).

An American Dagger caterpillar (Acronicta americana). It has just shed, and the yellower molt to the right is the cast-off skin of the previous instar. American Daggers are polyphagous, easting scores of different plant species, and are often one of the most common caterpillars that we find on nocturnal forays. I would note that polyphagous (many plants) diets are not the norm in the caterpillar world, specialization is.

The caterpillar of a Dot-lined White (Artace cribaria) becomes one with the branch that it's on. This is botanical mimicry writ large, although perhaps in this case it is lichen mimicry. I would note that iNaturalist's amazing identification app, when confronted with photos of this caterpillar, invariably only suggests various lichens as possibilities. I sometimes wonder how many of these we walk right past.

The stunning Radcliffe's Dagger caterpillar (Acronicta radcliffei) with its incredible bulbous black and red head. This species is a specialist on woody plants in the rose family (Rosaceae), particularly cherries. I think this one was found on a Black Cherry (Prunus serotina). Even though it isn't thought to be rare, I believe this was only the second one I've seen. We sometimes wonder if various caterpillar species, maybe this one included, occur primarily in the canopies of the trees in which they feed, out of view of ground-bound humans.

Always a coveted find, the Saddleback Caterpillar (Acharea stimulea). It isn't rare, in part because the caterpillars are polyphagous and can consume a large number of common plant species. Nonetheless, this must be a boom year for them, as our group must have found two dozen or so, far more than would be usual.

Note those fascicles of stiff spines. Some say that this species may have the most punishing sting of any North American caterpillar, and people with greater sensitivity to its venom can react very badly. They are envenomating spines. When triggered by touch, the spine injects venom from a sac at is base, much like a hypodermic syringe. I am told that the pain comes instantly, it is fierce and lasts for some time. Newbies, upon first seeing a Saddleback, usually call it cute. That they are, but potentially painfully cute.

That's it for now, but more cats are to follow...