You're sitting on your porch, trying to enjoy a quiet summer evening, when it starts. A rhythmic, rasping "ch-ch-ch" that sounds less like a bug and more like a miniature saw hitting a piece of wood. It's loud. Like, surprisingly loud. You might think it’s a cricket or maybe a lost cicada, but if it has that distinct, mechanical pulse, you're likely listening to a katydid.
So, do katydids make noise? Yeah, they do. In fact, they’re some of the loudest insects on the planet.
But here’s the kicker: they aren't "singing" with their throats. They don't have vocal cords. Instead, these lime-green insects are essentially living violins. They use a process called stridulation. Basically, they rub their wings together to create a sound that can carry for over a quarter-mile in the right conditions. It’s a fascinating, slightly chaotic symphony that defines the soundscape of North American summers.
The Mechanical Magic of Stridulation
Most people assume all bugs make noise the same way. They don’t. While cicadas use specialized drums in their abdomens called tymbals, katydids (family Tettigoniidae) are all about the wings. If you look closely at a male katydid—because, honestly, it’s usually the males doing the shouting—you’ll see a thick, vein-like structure at the base of their forewings.
One wing has a "file," which is basically a row of microscopic teeth. The other wing has a "scraper." When the katydid moves its wings, the scraper drags across the file.
Imagine running a credit card along the teeth of a plastic comb. Now imagine doing that at high speed and amplifying it through a hollow wing structure. That’s the noise. It’s abrasive. It’s persistent. And for the female katydid, it’s the most romantic sound in the world.
Why the Noise Changes Based on the Weather
Have you ever noticed that the woods sound different in July versus September? It isn't just your imagination. Katydids are cold-blooded. This means their metabolic rate is tethered to the ambient temperature. When it’s a sweltering 90-degree night, their muscles fire faster. The result? A rapid-fire, high-energy "Katy-did, Katy-didn't" call.
When the temperature drops in late autumn, the song slows down. It becomes a sluggish, raspy "katy... did..." almost as if the insect is running out of batteries. Researchers have actually used the chirp rate of certain orthopterans to estimate the temperature outside. It’s not as precise as a digital thermometer, but it’s surprisingly close.
Identifying the Players in Your Backyard
Not all katydid noises are created equal. Depending on where you live, you might be hearing entirely different "dialects" of insect noise.
The Common True Katydid (Pterophylla camellifolia) is the one responsible for the name. Their call is a three-pulse "ka-ty-did." They prefer the high canopy of deciduous trees. You’ll almost never see them because they look exactly like a leaf, and they rarely come down to eye level. You just hear them as this wall of sound vibrating from the oaks and maples.
Then you have the Bush Katydids (Scudderia). Their calls are much more subtle. It’s often a single, sharp "tick" or a soft shuffling sound. If you’re walking through a meadow and hear something that sounds like two pebbles clicking together, that’s your culprit.
Then there are the Meadow Katydids. These guys are smaller and often have a song that sounds like a spinning lawn sprinkler—a long, whirring buzz followed by a few chirps.
The Acoustic Arms Race
Why do they have to be so loud? It seems counterintuitive. If you’re a delicious, green snack for a bat or an owl, screaming your location at 80 decibels seems like a bad survival strategy.
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It’s a classic evolutionary trade-off.
The males are competing. In a forest filled with thousands of males, you have to be the loudest or the most distinct to get noticed. Females use these sounds to locate a mate in the pitch black of night. Interestingly, females have "ears" (tympana) located on their front legs, just below the knee. They literally walk toward the sound, pivoting their legs to triangulate exactly which branch the loudest male is sitting on.
Avoiding the Predators
Of course, predators aren't stupid. Bats have evolved to listen for these specific frequencies. In response, some katydid species have developed ultrasonic components to their songs that humans can't even hear. Others have learned to "stop and start." If a katydid senses a vibration or a sudden change in air pressure (like a bird landing nearby), it will go dead silent instantly.
Have you ever tried to find one? You follow the sound, get within three feet, and suddenly—silence. You’re staring at a wall of green leaves, and the insect has effectively vanished. Their camouflage is so good that even when you know exactly which branch they’re on, you probably won’t see them.
Is the Noise Dangerous or Harmful?
People often ask if the noise means an infestation is coming. Generally, no. Katydids aren't like locusts. They don't swarm in the billions and devour entire wheat fields in an afternoon. They are solitary for the most part.
While they do eat leaves, the damage they do to mature trees is negligible. You might see a few jagged holes in your hostas or oak leaves, but it’s rarely a cause for concern.
The only "danger" is to your sleep.
In high-density areas, the collective sound can reach levels that make it hard to hold a conversation on a patio. But honestly? It’s part of the seasonal rhythm. When the katydids stop making noise, it’s a sign that the first hard frost is coming. The silence of November is often more jarring than the cacophony of August.
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A Quick Comparison of Night Noises
It's easy to mix these up, so here is the breakdown of what you're actually hearing when the sun goes down.
Crickets usually have a musical, chirping tone. It’s a "chirp-chirp-chirp" with a rhythmic, melodic quality. They are mostly ground-dwellers.
Cicadas produce a buzzing, vibrating "drone." It often sounds like a high-voltage power line or a distant weed whacker. They are most active during the day and at dusk, whereas katydids own the night.
Katydids provide the "harsh" noise. It’s buzzy, raspy, and non-musical. Think of it as the "industrial" genre of the insect world.
How to Coexist with the Noise
If the sound is driving you crazy, there isn't a whole lot you can do short of cutting down every tree on your property—which is a terrible idea. Chemicals and pesticides are generally ineffective because the insects live so high up and are so dispersed.
The best approach is actually to embrace it.
- Seal your windows: Most katydid noise enters through gaps in window frames or thin glass. Heavy curtains or weather stripping can dampen the sound significantly.
- White noise: If the erratic pulsing of a katydid is keeping you awake, a fan or a white noise machine can help mask the frequency.
- Lights out: Katydids are attracted to light. If you have bright floodlights hitting your trees all night, you might be inadvertently inviting a party to your bedroom window. Switching to yellow "bug lights" or just turning them off can reduce the local population near your house.
The Role of Citizen Science
If you’re actually interested in the species making noise in your yard, there are some cool tools out there. The "Songs of Insects" project is a great resource for identifying specific calls. You can also use apps like iNaturalist. Even if you can't see the bug, a clear audio recording can often be enough for an expert to tell you exactly which species is keeping you awake.
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Understanding the complexity of these sounds changes how you hear them. It’s not just "noise." It’s a high-stakes survival drama playing out in the leaves above your head. Every rasp is a gamble, a plea for a mate, and a defiance of the predators lurking in the shadows.
Actionable Next Steps
- Identify the rhythm: Tonight, go outside and listen. If it’s a three-part "ka-ty-did," you’re hearing the True Katydid. If it’s a fast, continuous zapping sound, look for Meadow Katydids in the tall grass.
- Check the temp: Count the number of chirps in 15 seconds, add 37, and see how close it gets to the actual Fahrenheit temperature. This works best with crickets, but some katydid species follow a similar thermal rhythm.
- Check your lights: If you have a particularly loud "singer" right outside your window, try turning off your outdoor lights for two nights. You’ll likely find they move further into the yard.
- Observe the wings: If you happen to find one on a screen door, look at the base of the wings. You can actually see the "file" area that produces the sound. Just don't touch—while not venomous, a large katydid can give a surprisingly stout pinch with its mandibles if it feels threatened.