Will the real katydid please stand up?

Introducing the katydids of Martha’s Vineyard.

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Ms. Katydid of Martha's Vineyard. — Photo by Matt Pelikan

In much of the eastern United States, the name “katydid” refers most often to the true katydid, Pterophylla camellifolia. A bulky, leaf-like insect, this treetop species is well known for its call: a relentlessly repeated, three-note rasp, often transcribed as “kay-tee-did” (it sounds more like “cha-cha-cha” to my ears). As far as I know, this widely recognized insect is wholly absent from Martha’s Vineyard (let me know if you think you’ve heard one!).

But “katydid” is also a generic term, referring to a large group of green, grasshopper-like insects with long, threadlike antennae. The katydids we do have here (around a dozen species) all call, like their mainland cousin. But in general, our katydids are smaller and generally less obvious, because their calls (produced by rubbing specialized, textured wing parts together) are fairly quiet. And the insects themselves, shy and well camouflaged, are hard to see even if you know what you’re looking for. So these insects, despite being common and widespread, are almost unknown to the general public.

And they’re confusing even to the student of insects. It’s easy to tell one genus from another based on overall size and shape. But within each genus, the individual species are fiendishly hard to tell apart, very similar in color and structure. And the cryptic habits of these insect make it hard to learn anything about them.

Once in a while, though, I get lucky and stumble over a concentration of katydids that makes it possible to get acquainted. Such an opportunity came up recently as I rummaged among the grassy vegetation around a small, artificial groundwater pond (actually just a dry pond basin at the time of my mid-September visit) near the Correllus State Forest headquarters. This basin (I call it the HQ Pond) is the site of the only population I know of the slender meadow katydid, Conocephalus fasciatus.

I should be clear that this insect may be more widespread here than I’ve found it to be: My insect hunting tends to be focused on the Vineyard’s dry, flat sandplain portion, and since I’ve spent relatively little time in the wetter moraine, I could easily have overlooked a lot of slender meadow katydids! But this species clearly does associate with freshwater wetlands, and although it’s described in field guides as among the most abundant katydids, a shortage of its preferred habitat on the Vineyard likely means that it’s fairly scarce here.

But in any case, there were hundreds in evidence at the HQ Pond, and that fact right there got my attention. I believe the pond was excavated sometime in the past century; prior to that, the site was surely not slender meadow katydid habitat. So somehow this species must have discovered this little patch of wetland by wandering in from … where? The nearest similar habitats I can think of are a couple of miles away, in the Mill Brook valley or perhaps around a Great Pond cove head. For a species that I’ve never seen fly, the slender meadow katydid can really get around! I can only wonder how many decades the HQ Pond population has persisted for, perhaps with no influx of individuals from elsewhere to augment it.

The key to telling what kind of katydid you’re looking at lies mainly in what’s attached to the tail end of an adult individual: a blade-like ovipositor, or egg-laying organ, on females, of distinctive size and shape in each species; or the “cerci,” tiny paired appendages on the male abdomen, used for clasping females during mating, which are likewise species-specific in shape and color. A female slender meadow katydid has a straight ovipositor, about a quarter the length of the rest of the body and usually canted upward at a slight angle. On males, the cerci have a little outward turn at their tip and are bright green. I noted katydid after katydid with these features, gradually realizing that a species I thought of as rare here was, at least locally, abundant.

Even more surprising was the presence of large numbers of tiny immature katydids, or nymphs, which appeared to belong to the same species. In general, katydids and their relatives the grasshoppers overwinter as eggs, hatching in the spring, maturing more or less in unison during the summer, and laying eggs in late summer and fall. This schedule accounts perfectly for all the adults I was seeing. But those nymphs must have hatched months after the adults, and in mid-September, they clearly didn’t have time to mature before frost. The best I can suppose is that in this one species of katydids, as with a couple of our grasshoppers, some or all of the individuals break the pattern and overwinter as nymphs. I’ve found no mention of this in the literature on katydids, but I can’t think of another explanation.

This is how it goes with the study of insects: Most species are so poorly studied that you’re on your own for figuring out how, exactly, they live, and everything you discover leads to more questions. But I wouldn’t have it any other way.