On the long list of insects I’d like to see, one species near the top is the Northern mole cricket, Neocurtilla hexadactyla. The only known Vineyard representative of a small taxonomic family, Gryllotalpidae, that’s nested in among the true crickets, this is a truly bizarre insect.
As its common name suggests, it is fossorial, spending its time mainly in burrows it digs in sandy soil, usually near water. Its forelimbs, like those of its mammalian namesake, are stout and modified for digging. Its body is stocky and flattened, and with little need either to jump or fly, its hind legs and wings are greatly reduced. Difficult to see because of its habits, Neocurtilla is usually detected by the odd, quacking call of its males. In all respects, it’s the kind of odd, specialized insect that piques my interest.
Well, I still haven’t seen one! But the search led me to something equally interesting. While Northern mole crickets could be common here, for all anybody knows, there is only one location on the Vineyard that I’m positive hosts, or at least hosted, this creature. My friend Tim Simmons, as good a naturalist as you’re likely to find, reports hearing Neocurtilla routinely at Long Point decades ago, during Tim’s time as a biologist and caretaker there. But the species could be anywhere near water.
Visiting a south shore pond on August 29, I did as I always do, keeping an ear open for cricket calls, and searching any promising habitat I encounter for signs of mole crickets. I noticed an otter slide heading downhill to the shoreline. Otters, I figure, know where all the good stuff is, so I followed this track down to a small patch of damp sand at the edge of the pond. The spot, as far as my dim understanding of the species goes, looked like prime mole cricket habitat.
And by golly, there it was! Well, sort of. Or actually, not at all.
There was, to be sure, an oddly constructed, cricket-like insect with hunched posture and stocky, trowel-like forelegs. And it did, briefly, start to excavate in the sand, kicking an abortive spray of debris behind itself like an excited terrier. But things didn’t really add up.
For one thing, this insect was far smaller than I expected for a Northern mole cricket: a scant half-inch, rather than the full inch or more typical of Neocurtilla. OK, I thought, I’ve found a nymph — an immature individual, that is, which in Orthoptera resemble adults in structure but are smaller.
But the color was harder to explain away. While Northern mole crickets are flat brown in coloration, this little thing was black with reddish knees, and was distinctly glossy. That just seemed wrong. I got to work with the camera, managing a couple of dozen frames from several angles before the mystery insect hopped a foot or so into dense vegetation and disappeared.
The puzzle lasted no longer than it took me to get home and upload some of those photos into iNaturalist. Instantly and correctly, the artificial intelligence in that web platform recognized the insect as Neotridactylus apicialis, sometimes called the larger pygmy mole grasshopper. If I had ever even heard of it, I didn’t remember. It is the 69th species of Orthoptera known from Martha’s Vineyard.
Yes, grasshopper! I don’t know the details, but taxonomists place this insect in a small family in the grasshopper suborder. It is, in other words, only distantly related to Neocurtilla hexadactyla or any other cricket. But these two species have evolved similar lifestyles and, accordingly, strikingly similar body forms and habitat preferences.
I’ve been able to learn little else about this mole grasshopper. It eats, says bugguide.net, not very helpfully, “organic material such as algae.” It ranges across a good portion of the U.S., from Maine to Florida, Texas, and the Southwest. And while it may actually be quite common, it’s not often encountered, which is what you’d expect for a small insect that lives in tunnels, may be active mainly at night, and prefers habitat that can be inconvenient to explore.
I mentioned my discovery to Tim Simmons, who replied that he has had probable sightings of the species at Sepiessa Point and on Nantucket. So Neotridactylus may be out there in respectable numbers, just evading detection. I promise to look hard, now that I know that this species exists. And no, I haven’t given up on finding Northern mole crickets!
Like a lot of my more entertaining experiences in the study of insects, this episode hinges on a misidentification. And my initial error illustrates the way the human mind will tie itself in knots to make what you see fit with what you expect to see.
But the moment also reminds me that natural diversity is virtually unending; that evolution moves in surprising ways; and that otters do, in fact, know where all the good stuff is.
