Arthropods of Crowley's Ridge and Arkansas

A Selection of Annotated Galleries

For the past fifteen years my wife Cheryl and I have been studying and photographing the invertebrate fauna of Crowley's Ridge, a "sky island" rising up out of the Mississippi Delta.

An anomalous feature rising out of the otherwise flat delta in northeast Arkansas and southeast Missouri, Crowley's Ridge is possibly a unique feature in the world, tilted up by an earthquake in the late Cretaceous, when the area was at the bottom of an inland sea. The 1811-1812 New Madrid earthquakes (signs of these powerful 200-year-old earthquakes are readily visible today) show this is still a region of puzzling seismic activity, despite being far from any plate boundaries. The area is considered a "failed rift" where the continent thought about dividing, then changed its mind.

The Ridge begins up in Missouri, but we have only explored it from the point where it enters the northeast corner of Arkansas and then runs south for 150 miles, bisecting parts of eight counties, before it meets the westward-trending Mississippi River. It is nowhere more than a few hundred feet high, or a few miles wide.

The soft and highly erodible loess soil has helped create a landscape of high ridge trails

and steep-sided deep ravines. The Ridge, an island in the Delta, long isolated from other highlands, and relatively undisturbed by agriculture and the periodic flooding of the bottom lands, has its own distinct botany, including many relict species, and this extends to some insect species as well.

We are not trying to document "every" species of invertebrate. We are selecting groups that can be identified to species through close-focusing binoculars or close-up digital photographs (rather than only through collecting specimens). That generally means groups for which a good field guide exists, and groups which do not have an impossible number of species, since we like to strive for completeness (on Crowley's Ridge, we mean). Also, of course, we are looking for creatures that are particularly photogenic, and particularly charismatic. This after all is our keen pleasure, and what we want to share with you.

Note: these are open-ended albums: I constantly tweak them, adding new species, or improved photos, or new bits of behavior, or, all right, correcting errors. Increasingly, as a sort of appendix, I am adding species from throughout Arkansas, to make this, eventually, a guide to insects and spiders of Arkansas.

Galleries and Text

Editor's note: The galleries are designed to be read: each image has explanatory text (open with the circle-i button in the upper right) and leads into the the next as a slideshow. The links below take you directly to the first image in the gallery.

A good example would be butterflies. Super photogenic, lots of good field guides, and except for a few skippers, mainly readily identifiable through binoculars. Since we have a nearly complete collection of butterflies for the entire state, we have called this set "The Butterflies of Arkansas." We have found about 130 species in Arkansas. I have divided them into five albums. The first is Swallowtails and Whites and Yellows.

Next are the Lycaenids (also called Gossamer Wings), which includes blues, hairstreaks, and others.

Next, the Nymphalids, which includes all the "regular" butterflies.

The Skippers (Hesperiidae) are a subset of the butterflies. They tend to be smaller, more subdued in color pattern (orange, browns, and blacks), to have stockier bodies, and shorter, more triangular wings (which gives them terrifically fast flight: birds don't even try to catch them). Many are so similar to each other they offer real identification problems. They are like shorebirds to bird watchers: When you are a beginner, you dread them; with more experience you begin to love them for the challenge.

And finally the Grass Skippers, another difficult group.

Here's a smaller group of some very charming but easily overlooked creatures, the Tiger Beetles.

Dragonflies are probably next after butterflies and moths as favorite insects to study and photograph. In this album I have 56 of the 60 species that have been recorded on the Ridge, plus a good sampling of other species found in Arkansas.

Damselflies, the frailer suborder of dragonflies, are smaller and less dashing then dragonflies, but are just as attractive.

Moths are such a huge group (thousands instead of hundreds of species) that there is no way to try for completeness in recording them. Still they are popular, attractive, ecologically important. They can't be ignored altogether. The answer is to choose smaller groups among the moths to work with. For instance, in this album I have specialized in Underwing Moths, and wasp-mimic moths.

In this album I specialize in the hawk (or sphinx) moths, paying particular attention to their often spectacular hornworm caterpillars.

In this album I record moth caterpillars in general. It's my favorite moth album, as the caterpillars are often more interesting and attractive than the sometimes dull-colored and rather ordinary adult moths that they turn into.

The Grasshoppers are perfect for an undertaking like this. There are probably about 70 species in the state. We have recorded here some 55 species, and we are now beginning to add katydid and cricket species. They are all highly photogenic, and with close attention to detail (well, very close attention) are generally identifiable.

Here is our first attempt at non-insect invertebrates. Spiders are not ideal subjects in some ways: there are probably 450 species in the state, which is way too many to handle here, the majority are in the 3 mm size range, many are so similar to one another they can only be identified to species through microscopic examination of genitalia, and several only come out at night. Nevertheless they are hugely important ecologically and full of interest behaviorally and not without their own form of beauty. This first of four albums goes from tarantulas to orbweb-weavers.

This second of four spider albums goes from Wolf Spiders to Fishing Spiders.

This third of four spider albums goes from Jumping Spiders to Crab Spiders.

This fourth of four spider albums has all the rest, including Feather-legged Spiders, widows, recluses, spitting spiders, and others.

Here is our favorite group, the Robber Flies (Family Asilidae). These sometimes tiny and inconspicuous but sometimes large and spectacular predatory flies are always the primary predators in their particular ecosystem. Like six-legged falcons they wait on an exposed perch and fly up in an instant to seize a dragonfly or hornet or whatever else enters their air space. There is no field guide to these insects, but there ought to be. When Herschel Raney and I started studying them in the early 2000's we had to learn them one at a time, taking specimens and searching the literature for identifications. My website is meant to serve as a field guide to Arkansas robber flies.