You may think you know what a cricket is. But “cricket” is a generic term, referring to a large and varied group of species. With grasshoppers and katydids, crickets make up the insect order Orthoptera; crickets are distinguished by having long antennae (unlike grasshoppers) and being generally less grasshopper-like than katydids. It’s a fascinating group, and a musical one: Crickets (along with katydids and some grasshoppers) produce “songs” by rubbing specially modified body parts together — a process known as stridulation. In the case of crickets, it’s generally roughened veins along a tough, leathery forewing that rub, and because the vibration resonates across the entire wing, cricket songs can be impressively loud for the work of such small animals.
The most accessible example of cricket stridulation comes from field crickets, of which the Vineyard has two, possibly three species. These are the large black crickets you find in your yard (and in your basement); their bodies are close to an inch long, and on females, a long, needle-like organ called an ovipositor protrudes from the tip of the abdomen. It looks dangerous but isn’t – its sole function is laying eggs in soil or leaf litter.
The two field cricket species I’m sure occur here are almost impossible to tell apart by appearance. But happily, the timing of their life cycles differs reliably. The spring field cricket hatches in the late summer, passes the winter as a hibernating nymph, and resumes growth when the weather warms in spring. By about early June, this species is fully grown and singing away in yards, meadows, and pastures. Spending the winter as an egg, the fall field cricket lags behind its cousin in developing, not reaching maturity until late summer. There is a brief period from late July to mid-August when I think both species can be heard; but by September, only the fall field cricket is active, and the difference in seasonality helps keeps these two closely related species from interbreeding.
The field crickets give the quintessential cricket song: a loud, relentless, but rather musical “crick, crick, crick …” The song is so familiar that many people barely notice it. But although these insects are easy to detect, they probably are not the most numerous crickets on the Island. That honor, I’m persuaded, goes to one of the field crickets’ smaller relatives, the so-called ground crickets. These insects resemble their heftier cousins, but as a group, ground crickets top out at about a half-inch in length. Some species barely break the quarter-inch mark.
Ground crickets, which mature and begin singing in mid-summer, produce sound in the same manner as their larger cousins, and the nature of the sound is therefore similar. But being smaller, ground crickets stridulate much faster, producing something more like a twitter than a series of well-spaced “cricks.” (Imagine a quickly rotating pulley with a squeaky pivot.) If you have ears and have ever been outside in the summer, you’ve surely heard several species of ground crickets without knowing it; while they occupy many types of habitat, ground crickets call day and night, and some species thrive in lawns and gardens.
But hearing one and seeing one are two different things. Ground crickets spend most of their lives concealed in leaf litter on the ground. Being both small and the same color as the debris they hide among, ground crickets are very, very hard to get a look at. By tracing the sound of a singing one, I can often narrow the search to a patch of ground a few inches square. But start poking around to find the singer, and your quarry shuts up and scuttles away. If you get a glimpse, you’re lucky, and if you can consistently get good looks at these creatures, well, you’re a better naturalist than I am!
The ground cricket species do differ in appearance, though, and even more so in how they sound; each species has a typical rate of chirping and distinctive tone quality. I’m gradually learning to distinguish them on this basis (at least three species occur widely on the Vineyard). And our other groups of crickets, which are no easier to see than the ground crickets, can similarly be recognized by sound: the tree crickets (a group of odd, ethereal, greenish bugs that sing sustained, musical trills), bush crickets or “trigs” (singers of scratchy songs from the ground and undergrowth), and even the mole cricket (never heard one myself, but I’m told they live here).
Masters of concealment, crickets are part of a vast community of insects that most people never see. But they’re out there, reproducing, eating, and being eaten, part of the huge web of life that surrounds us. And above all, they’re stridulating, millions of individual plucking sounds adding up to the soundtrack that characterizes a summer night. Abundant now, their numbers wane as the autumn progresses. Enjoy them while you can.