Among my favorite insects are the Vineyard’s three species in the genus Scudderia, known as the bush katydids. These are large insects, sometimes exceeding two inches in body length. Like all katydids, they feature prodigiously long, threadlike antennae and long hind legs adapted for jumping. They have fully developed wings, extending past the ends of their bodies, and when folded, these broad wings give their owner a leaf-like appearance that serves as camouflage.
The wings are also functional. When disturbed, bush katydids launch into slow but determined flight. Flight must be energy-intensive for them: Their escape flights are generally brief, no more than 50 feet or so, and they rarely rise more than six feet above the ground. But they’re capable of better than that when motivated, and I’ve seen an irritated bush katydid rocket up to treetop height, level off, and head for the horizon.
When undisturbed, bush katydids lead lives of quiet deliberation, perched on low vegetation either woody or herbaceous. They are rarely observed on the ground. They feed mainly on plant material, clambering with dignified grace as they forage, and they spend a high percentage of their time just sitting, conserving energy and staying concealed from predators. Like a lot of Orthoptera, they vary their diet with a little scavenging of other arthropods, and perhaps even a little recreational predation.
My first encounters with Scudderia were, like all my early experiences with Orthoptera, somewhat bewildering. I knew they were katydids, and that was about it. But it’s the curiosity prompted by my own ignorance that impels me to study the natural world, and having started noticing bush katydids, I inevitably wondered what species occurred here, how they lived, and how the species differed. So I watched, read, and asked questions.
The genus Scudderia, as a whole, is relatively easy to recognize. The Vineyard also hosts two other, closely related genera, and details of wing shape and body proportions sort them out pretty readily. But within Scudderia, telling the species apart can be challenging, and it took me years to develop the knack.
Definitive identification comes most easily from a good look at the end of the abdomen of a Scudderia. Males have a feature there called the supra-anal plate, reduced almost to nonexistence in one of the species, but a distinctively shaped projection in the other two. On females, an organ called the ovipositor extends from the end of the abdomen. This is used for placing eggs in appropriate places, and in Scudderia, ovipositors are curved, bladelike instruments. The degree of curvature varies from species to species, and on one of our Scudderias, S. furcata, the ovipositor seems invariably to be reddish. So like the male supra-anal plate, ovipositors are a powerful ID cue.
Regrettably, the luxurious wings of a bush katydid often obscure the end of the abdomen. So I often resort to nabbing a Scudderia for a quick view, and possibly a photograph, of the important anatomy. These calm, slow-moving insects are easy to catch, and while the legs break off pretty easily if you’re careless, a finger-and-thumb pinch grip on the wings is easy to manage and safe for the insect. (Katydids missing legs are surprisingly common, and don’t seem to be at much of a disadvantage.) In contrast to many other katydids, Scudderia rarely bites when being handled.
But some katydids can’t be caught, and I generally prefer to avoid intruding that aggressively into their lives. So over the years, I’ve worked to learn other indicators for identification. More subjective and less reliable than the abdominal appendages, these traits can still produce correct IDs.
Scudderia septentrionalis is smaller than its relatives, with broader wings. The veins on its wings seem oddly loose to me, somehow netlike relative to the wings on our other two species. Slightly larger, S. furcata has longer, narrower wings, rather rectangular in shape, and the base of the front femora (the uppermost major section of the leg) is yellowish. Our largest bush katydid, curvicauda, has ovoid wings and longer hind legs than its cousins. The rear edge of each hind tibia (equivalent to our shin or forearm) is reddish on this species, but green on the others. Each of these species has its own shade of green; I can’t describe the difference in words, but color alone is often enough to suggest an ID.
Our Scudderias differ slightly in seasonality, with adult septentrionalis beginning to appear as early as late June. S. curvicauda is next, its first adults appearing a couple of weeks later, and it is not until August that I start to find adult furcata. Of the three, septentrionalis seems most likely to turn up in human-modified habitat. S. furcata prefers scrub oak habitat, but successfully uses a wide range of environments. And curvicauda is the specialist among our bush katydids, bound tightly to scrub oak barrens, with every Vineyard record I’m aware of coming from within Correllus State Forest.
It has taken me 16 years to get this well-acquainted with these insects, but it has been time well spent. They’re gentle, charismatic insects, well worth knowing.
