August 30, 2022
I’m sitting in the shade of a ponderosa pine on this hot afternoon, looking out over the bunchgrasses and sagebrush of the dry, shaly hills above Spokane Bay. First I notice the sound in the distance, a bit absentmindedly. It’s a sharp, crackling snap, repeated several times, then followed by a rapid buzz. The sound is coming from grasshoppers in flight, I vaguely notice.
Then all of a sudden, there’s one just ten feet from me, snapping over the bunchgrasses. The sound is impossible to ignore now. He’s a large grasshopper, his hindwings pale yellow, snapping vehemently as he hovers three feet over the grasses. Another grasshopper is responding from 20 feet away in an emphatic contest of crackles and snaps.
I’ve become much more aware of singing insects this year, and I’ve started to learn a few of their songs. It’s going to take me a long time to learn all of them – especially the ones that sing from a hiding spot in the grasses, falling silent when I approach. But this one is extremely visible and hard to ignore. I decide to collect him and learn his story.
Catching the grasshopper
I don’t have an insect net with me, so my hat will have to do. As I walk towards his noisy hovering, he obligingly lands. On the ground, he blends in, a sand-colored lump against the shale. I inch forward and swipe with my hat, covering him. Success! Except that now I can’t see where he is. I slowly reach under my hat for him, and he escapes, leaping into flight.
We repeat this performance five or six times, traveling up and down the steep, dry slope. Finally, I manage to grab him from under my hat.
As always, collecting an insect isn’t something I do lightly. But I’m happy to see that these grasshoppers seem to be reasonably common here. Right now, I can hear five others within earshot, and undoubtedly there are more in the distance.
Getting to know Circotettix undulatus
The next day, in the lab, I’m able to identify this grasshopper. He’s the Great Basin crackler, Circotettix undulatus. And, as I had hoped, identifying this grasshopper sheds some light on what it’s doing here. I’m using Daniel Otte’s several-volume set, The North American Grasshoppers, a thorough work that serves as both identification manual and biological reference. And according to Otte, Circotettix grasshoppers are known for their noisy aerial snapping. It’s the males that do the snapping, attracting females with their loud antics. Like singing birds in the spring, these grasshoppers are performing in pursuit of love.
Among the Circotettix grasshoppers, Circotettix undulatus is near the edge of its known range here in Helena. This is a species of the interior west, from the Cascade Mountains and the Sierra Nevada to Idaho’s Snake River Plain and the western portions of Montana. But you can’t find it everywhere within this range. Circotettix undulatus is a species of rocky hillsides and cliffs – habitats with sparse vegetation and few other grasshoppers.
How will you know this species if you see it? Look for a large, noisy grasshopper in rocky areas. The forewings are a mostly uniform brownish, the hindwings pale yellow with a faint, dark smudge near the tip. The hind tibiae are bluish. And while males of other Circotettix species also make loud display flights to attract females, Otte writes that only Circotettix undulatus has a song with two distinct parts: a slower series of snaps followed by a faster buzz.
Wing-snapping mystery
While I was identifying this Circotettix, Dr. Grant Hokit stopped by and asked me how these grasshoppers make their noises. Once again, I turned to Otte. He writes that male band-winged grasshoppers “fly up from the ground, snapping their hindwings and flashing their contrasting wing colors.” In the case of Circotettix undulatus, Otte estimates that the males snap their wings 15 to 25 times per second during the buzzing part of their display.
It appears that the actual biomechanics of grasshopper wing-snapping haven’t been studied very thoroughly. I did find one study from 2021 that investigated this question in the Chinese grasshopper Acrida cinerea. Using tethered grasshoppers, free-flying grasshoppers, and high-speed video, these researchers found that Acrida males produced a snapping sound by clapping their hindwings together at the top of a wingbeat.
Is this how Circotettix undulatus produces its snapping song? Do these males clap their hindwings together 15 to 25 times a second to produce their noisy buzz? As far as I know, no one has studied this question.
Nature is amazing. The wingbeats of these grasshoppers are as incomprehensible to me as the drumming of a downy woodpecker. How does an animal move so fast?
I have no idea – and for now, I’m okay with that. And next time I’m sitting on a steep, rocky slope near the end of summer, listening to the Circotettix undulatus performing their mate-attraction display, I’ll be able to recognize them and wonder about the mystery of their wingbeats. Now you can, too.