Thursday, August 31, 2017

Caterpillar season is upon us!

Well, caterpillar season is really year 'round, but in terms of mature specimens and conspicuousness, late summer and fall are best. I've been afield a lot of late, and have been seeing plenty of the tubular crowd. The following pictorial display is of specimens that I've seen and photographed in the past week, mostly in southern Ohio's Adams and Scioto counties. The variation in caterpillars is mind-blowing, as is their appearances.

FINDING CATERPILLARS: When I share photos such as these on social media, someone(s) will invariably ask how to find caterpillars. Because, for the most part - even though there are probably well over 2,000 species in Ohio - they are out of sight and out of mind. The biggest thing one must do is venture out after dark. Most caterpillars become active under cover of darkness; an evolutionary response to bird predators and various predatory insects that are mostly diurnal, no doubt. During the day, most caterpillars secrete themselves exceptionally well, and are much more difficult to locate. Searching the undersides of leaves should yield results, and a good flashlight is essential. Best of all are UV blacklight flashlights, as many caterpillars glow brightly under such beams. A good knowledge of botany is hugely helpful, as many species are keyed to certain plants. Some plant groups, such as grapes and oaks, are major search sites for caterpillar-hunters, as they often yield fabulous cats. Best of all is getting afield with experienced searchers. I've taken out people who have never caterpillar-hunted many times, and it's always fun to see their reactions as various fantastic bags of goo come to light.

A fabulous leaf-edge mimic, the Checker-fringe Prominent, Schizura ipomoea. They feed on tree species with jagged leaf margins, and the back of the caterpillar matches the shape of the leaf quite convincingly. I see these feeding boldly during the day on occasion; apparently their disguise is so effective that birds often overlook them. The scientific name's specific epithet, ipomoea, is an apparent misnomer. It refers to a genus in the morning-glory family, a group of plants this caterpillar was apparently erroneously recorded as feeding upon, but probably never does.

"... slug caterpillars seem more fantasy than reality." From David Wagner's epic Caterpillars of Eastern North America book (2005). This, by the way, is the book to get should you want to learn more about caterpillars.

This extraordinary beast is a Nason's Slug Moth caterpillar, Natada nasoni. Virtually all of the slugs cats, a few more of which appear below, are exceptional in appearance. The rather distasteful name for these beautiful creatures stems from the caterpillars, and their peculiar gliding mode of locomotion.

A Luna moth caterpillar, Actias luna, appears to glow from within. Unlike the tiny slug cats, this one is a thumb-sized whopper and often stands out from afar under a UV light. We frequently find them on black walnut, but Luna cats will eat a variety of woody plant foliage. The adult moth is one of the most beautiful and widely recognized of our North American moths.

Rather alien in appearance is this Silver-spotted Skipper, Epargyreus clarus, larva. They're most easily found on black locust but feed upon other members of the pea family including hog-peanut, which is what I found this one snacking on.

Another fantastic slug cat, this one the Black-waved Flannel Moth caterpillar, Megalopyge crispata. It resembles a turtle covered in brown shag carpeting, or perhaps Donald Trump's hair. Caterpillars grow through molts, and often look very different at different growth stages. The stages - termed instars - preceding this one look utterly different. The caterpillar above is in its final instar, but earlier ones are white with exceptionally long hairs - like ill-kempt cottonballs. Look, but don't touch - this species is beset with stinging spines capable of delivering painful stings.

A bizarre Camouflaged Looper, Synchlora aerata, feeds upon the flowers of stiff goldenrod. These flower-specialist inchworms adorn their bodies with flower parts of whatever it is that they're eating. Those are goldenrod flower petals projecting from its body. The moth it will become goes by a different name, the Wavy-lined Emerald.

One of our more bizarre larva is the Red-washed Prominent, Oligocentria semirufescens. That's the head at the left, overarched by a strange rhinoceros-like horn. When this beast is eating leaves dappled with browning necrotic tissue, it can blend in amazingly well. I believe it was sharp-eyed Laura Hughes who spotted this one on an Adams County foray, and I'm glad she did - it's only about the third one I've seen.

PHOTO NOTE: I shot this image in the field, as with all the others in this post. The interesting blue background is someone's shirt. The quality - mainly color and blur - of a photo's background is known as the bokeh. Creating an effective bokeh that complements the subject is vital, and the photographer should pay great attention to what's in the background. Bokeh can be artificial, too, by having someone stand behind the subject as in this image, or by holding colored pieces of paper in the backdrop, or leaves or other natural material. Often highly effective are black backgrounds. This look is achieved with flash, and by ensuring there are no objects within five or so feet behind the subject. Then, at least in many situations, the flash causes the background to go black.

This one looks like it came right off a coral reef in a tropical sea. It's the Stinging Rose Caterpillar, Parasa indetermina. Like many caterpillar species, they have boom and bust years, but can be fairly easy to find in seasons of plenty. They'll feed on a wide variety of woody plant foliage.

PHOTO NOTE II: Good general camera settings when shooting caterpillars are f/11 to f/16, ISO 100 to 200, and shutter speed of 1/200. Flash is mostly essential, and flash units that mount atop the camera on the hotshoe will probably always beat the built-in flash. I shoot Canon cameras, and have two types of flashes, both of which excel for caterpillars and other macro subjects. One is the Canon 600 II Speedlite, the other the Canon MT-24EX Twinlite.

Finally, another amazing slug cat, this one the White Flannel Moth caterpillar, Norape ovina. It looks like a jeweler studded the little beast with emeralds. Like the other species in this post, this one is at least fairly common in many areas, and is often easily found during nocturnal searches.

So, if chance permits, get afield under cover of darkness and inspect the leaves. You never know what might come to light!

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2 comments:

Anonymous said...

It is obvious that I left too early.

mary said...

Hey Jim- Thanks for the great post on cats! I had never thought to look for them at night. I am wondering how late into the season you can usually find good specimens? I'll be leading a night hike in late October and wondered if I could see cats then. Thanks!