Katydids have their ears near their knees

 

Up close with a Greater Anglewing katydid (Microcentrum rhombifolium). Katydids "sing" with their wings, rubbing the bases together in a process known as stridulation. One wing contains a file, the other a scraper. In the case of the Greater Anglewing, males create a series of soft clicks, as if two pebbles are being tapped together. It stands to reason that these insects would have good hearing, as males create the songs to attract females or maintain unique territories. Indeed, they do hear well, courtesy of ears on their forelegs, just below the knee. It's that elongate vertical slit on the katydid's foreleg in the photo.

Katydids and their orthopteran allies represent the genesis of intentional sound. Fossil records of katydid relatives date back 250 million years ago, replete with the file/scraper sound system. Although life on earth began over 3.5 billion years ago, the earliest animals were mute. Animal sound didn't originate until the katydids came along, and over the eons the faunal soundscape has evolved into a gorgeous, complex aural tapestry that involves legions of different animals making their own types of music.

Alas, the orthopteran symphony will soon cease at northerly latitudes, like where I live in central Ohio. But they're still going strong, and we've probably got another two weeks or so to enjoy their ancient melodies.

A greater Anglewing poses on the foliage of Winged Sumac (Rhus copallinum). The large katydid is a remarkable leaf mimic.

Greater Anglewing - master of disguise

The orthopteran symphony is nearing its crescendo right now. Various crickets, trigs, coneheads, and katydids are chirping, rasping, scraping, trilling, and making all of the other sounds that they do. In spite of the absolutely dominant wall of sound that these "singing" insects create, especially at night, how many of them do you actually see?

I was hiking in Adams County today, when an anomaly on the leaf of an eastern cottonwood caught my eye. Look closely. This photo is unmodified other than to compress it so that it would upload to Blogger.

I  flipped and cropped the photo here, so that the entire animal fills the photo. It is one of our more ubiquitous katydids, the greater anglewing, Microcentrum rhombifolium. You've got them in your yard. The males make an extremely distinctive series of clicking notes that accelerate as the song progresses. They also deliver short harsh zziiiit! notes. Listen to a greater anglewing HERE, and see if that's a sound you've heard before.

When an anglewing is not on a green leaf, they're a bit like a fish out of water. This is one we captured on a night foray a few years ago, and posed on someone's sleeve.

But when they are resting on vegetation, it isn't hard to see why we hear far more of these leaflike singers than we ever see.