Coneheads

Often heard but rarely seen.

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A round-tipped conehead or Neoconocephalus retusus. -Matt Pelican

On any mild October night — assuming we get one — you can step outdoors virtually anywhere on the Vineyard and hear insects singing. What exactly you hear depends on where you are. But male crickets and katydids of various kinds will be holding forth in a chorus of chirps, trills, and buzzes, hoping a female of their species will be favorably impressed.

With practice, it’s possible to recognize these songs, since each species gives a distinctive one. But that practice is hard to get: Crickets and katydids are masters of concealment, and it is infuriatingly difficult to get a look at one of the singers, even if you locate the source of a call to within inches. Camouflage, wariness, and a knack for keeping leaves and branches between themselves and any possible threat make it hard to learn what species is making a particular call.

Exhibit A might be a smallish group of katydids known informally as the coneheads, either a tribe or a subfamily depending on your source, comprising four genera and about two dozen species in the continental United States. (Go ahead. Let’s get all the “Saturday Night Live” conehead jokes out of the way right now.) Medium-size in katydid terms, coneheads average roughly two inches in length, and they appear in green and brown forms. Like other katydids, they’re equipped with powerful, elongated hind legs that are optimized for jumping (though they can also fly). A conehead’s slender, elongated body is tipped at the front end with an odd little cone-shaped blip that gives the group its name.

The purpose of these forehead-mounted cones has not been satisfactorily explained, but at least in part they must surely have something to do with helping coneheads distinguish members of their own species from relatives. In each type of conehead, the cone has a distinctive shape and color or pattern of color; while there are other ways to identify coneheads that you’re lucky enough to get a good look at, examining the cone is by far the easiest and most reliable method.

Like other katydids, coneheads produce their song by stridulating — that is, rubbing specialized portions of their forewings together. The process, if you get a chance to watch it, doesn’t look especially impressive: The wing motion is fast but slight, as if the insect were shivering. But in sonic terms, the results can be quite spectacular: Some of the coneheads achieve incredible volume, rivaling the cicadas as the loudest insects in our region.

So far I’ve found only two conehead species on the Vineyard. One, the round-tipped conehead, is fairly common. Named for the neatly semicircular margin of its cone, this species is never numerous, but turns up quite widely in brushy meadows and woodland edges. Its call is quite distinctive: If you learn to recognize it, you’ll quickly get a sense of how widespread this conehead is on the Vineyard. A prolonged, dry buzz, the round-tipped conehead’s call is often described as “wiry” and suggests to my ear the sound of a faulty electric circuit arcing.

Less common but still quite broadly distributed on the Vineyard is the larger robust conehead. Places I’ve heard this species calling from include a patch of dune grass at Eastville Beach, roadsides in Chilmark, West Tisbury, and Vineyard Haven, and my yard in Oak Bluffs. The call may be the most distinctive noise made by any of our insects: an unceasing buzz with harsh, grating tone, given at a deafening volume (literally, this species hurts to listen to if you get too close). Both of our conehead species turn up occasionally at porch lights, and finding one there may be the easiest way to get a look at one.

While their behavior is fairly flexible, coneheads generally prefer grasses and herbaceous vegetation to trees and shrubs. And a calling male is not bashful: Both of our species call both day and night, and a male will keep his buzz going as you approach, shutting up only when you move your ear to within inches of his location. If you haven’t spotted him by that point, you’ve likely missed your opportunity. Disturbed, a conehead typically drops head first straight down into the leaf litter. The massive, spiny hind legs, while designed for jumping, also work well for powering the insect down into the dried debris; just a second or two after he drops, a conehead will be fully concealed, motionless, and virtually impossible to find.

Female coneheads possess long ovipositors — spike-like organs at the end of the abdomen, designed for laying eggs inside the stems of plants. (The ovipositor shape and length are useful ID cues if you happen upon a female.) Eggs, laid in late summer or fall, overwinter within the stems they were deposited in and hatch in late spring. Like most of their relatives, coneheads resemble their adult selves upon hatching, and mature over a period of six or eight weeks by passing through a series of five increasingly large stages, or instars, before a final molt brings them to maturity.

Living on a diet of plant material and soft-bodied insects such as aphids, coneheads are themselves prey for predators ranging from birds to large spiders. But in spite of their relative abundance and their active roles in the ecosystem, their cryptic habitats make coneheads somewhat mysterious, often heard but rarely noticed or seen.