I love to hear thine earnest voice,
Wherever thou art hid,
Thou testy little dogmatist,
Thou pretty Katydid.
— Oliver Wendell Holmes, “To an Insect”
While summer days are filled with the songs of cicadas, as I wrote about in my last column, at night the katydids take over, and there are many more species of them.
Each katydid species makes a different sound, although sorting them out can require an expert. In their book “The Songs of Insects,” Lang Elliott and Wil Hershberger describe the array of sounds as “high-pitched raspy squawks, buzzes, and shuffles.” The best way to determine the singers is to listen to audio clips (see sidebar on listening to bug music). One summer, with the help of their book and the accompanying CD, I tried to identify all the night sounds that I thought were from katydids. After figuring out a few, I gave up, partly because their cousins, the crickets, were joining in and some sounded like katydids. Both are in the order Orthoptera, which also includes grasshoppers, a few of which also sing.
Orthopterans produce sound differently from cicadas, which are in the order Hemiptera (bugs, or true bugs, since entomologists tend to call all insects “bugs”). While male cicadas use a sound chamber (tymbal) to call for mates, orthopteran males use “stridulation” — rubbing of one body part against another. Male katydids and crickets have forewings that have a sharp edge or “scraper” on the upper surface of the lower wing that they rub against a row of bumps known as the “file” on the underside of the upper wing. Sue Hubbell, in her celebration of invertebrates, “Broadsides from the Other Orders: A book of bugs,” aptly compares the sound to “drawing a fingernail along the teeth of a comb.” When they sing, katydids raise their wings, which vibrate from the scraping.
Female katydids receive the males’ sounds through drum-like membranes in their legs. In most katydid species, only the males sing. A noted exception is the great angle-wing katydid (Microcentrum rhombifolium), which is more widespread than the common true katydid but has a less charming song. Some katydid species, perhaps to keep predators from finding them, don’t call but rather stamp and thump on twigs to create vibrations. The females of their species pick up the sounds through their “delicate mechanoreceptors,” Hubbell explains.
The etymology of the word “katydid” is hard to nail down. Two of the best-known legends ascribes the name to a person — a girl who is a willful liar, or a scorned wife who kills her husband. Hubbell offers another possibility: that it is derived from the Greek for “meaning to resound, to din in one’s ears.” hence Oliver Wendell Holmes’ referring to the bug as a “dogmatist.”
Katydids are roughly divided into six groups, five of which inhabit our area: conehead, meadow, shieldback, true and false. (“False” katydids are not pretenders but rather were misnamed merely to separate them from the katydids dubbed “true” for some reason I have yet to discover). In their book, Elliott and Hershberger include two dozen katydid species that are common in the Virginia Piedmont and Blue Ridge, the most iconic of which is the common true katydid (Pterophylla camellifolia).
The loudest and perhaps one of the most melodic, the common true katydid is also one of the few that sings out “ka-ty-did,” in a rising and falling chorus with variations across its range. Here in the Southeast, its song is composed of three to five pulses delivered rapidly, which together sound like a brief rattle. When lots of males are singing in the same location, they organize into two groups, each singing alternately but in synch with the other rhythmically. The resulting call and answer can sound like a friendly argument about Katy’s guilt: “ka-ty-did,” “ka-ty-did-n’t,” and so on through the night. Together, Elliott and Hershberger write, their songs can produce a “resounding pulsation of sound that can overwhelm the listener.” (See the sidebar on the loudest katydid species.)
Singing from high in the trees, particularly oaks, the common true katydid doesn’t fly and so is seldom seen. Closer to the ground, I often hear and see the “false” oblong-winged katydid (Amblycorypha oblongifolia). Rather than singing its name, it delivers a buzzy zeee-dik every few seconds. One sang under my bedroom window all summer on year, and the intermittent zee-dik was far from the lullaby the common true katydid delivers. While the eastern katydid is “built like a tank,” as Elliott and Hershberger put it, most katydids, including the oblong-wing, are slender.
With bodies measuring up to three inches here in North America, katydids present a huge, protein-rich meal for a wide variety of predators. The only defense these orthopterans have is blending in with their surroundings. Most eat green foliage, so are a lovely bright green with leaf-like veins in their wings. Some have intricate, if subtle, designs on their bodies that add to their beauty.
Philosopher and jazz musician David Rothenberg, in his book “Bug Music,” takes a fascinating journey into “how insects gave us rhythm and noise,” as the book is subtitled. “They are always there,” he writes, “singing behind everything else in the forest. Are they then the background to human life, grounding our music, or have they a clear part in our music? When we hear them synchronize with our shaman beats, we want to smile, because we believe we belong.”
Temperature affects the rate and pitch of the katydids’ singing. In the middle of the night, the pulsing song of the common true katydid can become a slow, low-pitch chant as temperatures fall. With days shortening in autumn, I often hear this katydid singing high in the Blue Ridge Mountains in the middle of the day, taking its last shot at breeding. Hearing its song then is bittersweet, for it’s a sign of the winter to come, when the chorus of insects falls silent.
© 2018 Pam Owen
Listening to bug music
To hear the sounds of singing insects, go online to “Songs of Insects” or the Macaulay Library. The books “Bug Music,” “The Songs of Insects” (with CD) and “Broadsides from the Other Orders” are available at the Rappahannock County Public Library.
Loudest insect in North America?
In the far western reaches in Virginia and throughout the Midwest resides what is thought to be the loudest insect in North America, the robust conehead katydid (Neoconocephalus robustus). It is so loud that “at close range, it becomes painful to listen to,” Elliott and Hershberger write. “One would think that the insect would burst into flames from the friction produced in creating such an intense song.”
The robust conehead also has the fastest stridulatory wing-stroke rate of any katydid — 208 cycles of wing movement per second, according to University of Florida entomologist Thomas J. Walker In the right conditions, it can be heard from more than 1,500 feet away.