How One Moth Species Can Jam Bats’ Sonar Systems

In a species of tiger moth native to the Arizona desert, scientists have discovered a new weapon in the endless evolutionary arms race between predator and prey. New research shows that the moths, Bertholdia trigona, have the ability to detect and jam bats’ biological sonar – the technique that allows bats to “see” through echolocation. The moths’ remarkable ability, which as far as scientists know is unique in the animal kingdom, allows the insect to evade hungry bats and fly away.

Evidence of this ability was first uncovered in 2009, by a group led by Aaron Corcoran, a wildlife biologist who was then a PhD student at Wake Forest University. “It started with a question has been out there for a while, since the 1960s—why do some moths produce clicking sounds when bats attack them?” Corcoran explains.

Scientists knew that most species of tiger moths that emitted ultrasonic clicking sounds did so to signal their toxicity to bats—similar to how, for example, poison dart frogs are brightly colored so that predators can easily associate their striking hues with toxic substances and learn to look elsewhere for food. This particular species, though, emitted about ten times as much sound as most moths, indicating that it might be serving a different purpose entirely.

To learn more, he and colleagues collected trigona moths, put them in a mesh cage, attached them to ultra-thin filaments to keep track of their survival, and introduced brown bats. “If the sounds are for warning purposes, it’s well-documented that the bats have to learn to associate the clicks with toxic prey over time,” he says. “So if that were the case, at first, they’d ignore the clicks and capture the moth, but eventually they’d learn that it’s toxic, and avoid it.”

But that wasn’t what happened. The bats didn’t have to learn to avoid the moths – rather, Corcoran says, “they couldn’t catch them right from the beginning.” The reason for this, they determined, was that the moths were using the clicks to jam the bats’ sonar.

A bat’s sonar works like this: Normally – because they hunt at night and their eyesight is so poorly developed – bats send out ultrasonic noises and analyze the path they take as they bounce back to “see” their environment. But when approached by the bats, the moths produced their own ultrasonic clicking sounds at a rate of 4,500 times per second, blanketing the surrounding environment and cloaking themselves from sonar detection. “This effectively blurs the acoustic image the bat has of the moth,” Corcoran says. “It knows there’s a moth out there, but can’t quite figure out where it is.”

But the experiment left a remaining question: How did the moths know when to activate their anti-bat signal? The team’s latest work, published this summer in PLOS ONE, shows that the trigona moths are equipped with a built-in sonar detection system.

As the bats approach, they increase the frequency of their calls to paint a more detailed picture of their prey. Corcoran’s team hypothesized that the moths listen to this frequency, along with the raw volume of the bats’ calls, to determine when they’re in danger of attack.

To test this idea, he attached tiny microphones to moths to record the exact sounds they heard when attacked by bats. He also stationed microphones a few feet away. The mics near the moths heard a slightly different sound profile of approaching bats. Then, he played each of these sounds to an entirely different group of moths to see their responses.

The moths that heard the recordings only began emitting their own ultrasonic noises when the researchers played the sounds heard by the moths actually in peril—and not the sounds that would be heard by moths a few feet away from the one in danger. By analyzing the two acoustic variables (volume and frequency), the moths could effectively differentiate between the two.

The moths click “only when they can confidently determine that they’re getting attacked,” Corcoran says. This makes sense, because the ability to figure out exactly when they’re in danger is particularly crucial for this species of tiger moths—unlike other, toxic species, these ones taste good to bats.

Comment: This is the entire story. Given our recent discussions of drones, anti-drones and EW, I think this is both an interesting and appropriate story. It shows how intricate and ingenious nature can be in the age old struggle between predator and prey. I rank it right up there with my ode to the dung beetle and her celestial navigational skills.

The human art of war can be just as intricate and ingenious. Years ago I did a lot of collection on what was then called battle management systems. I never did anything so dramatic as arranging the theft of one of these systems or even just the software. But I did manage to obtain the minute cues used by the algorithms to determine the identity of a potential target. With that information, our weapons designers and software developers could mask or modify those very particular cues and thwart those battle management systems. 

Modern AI is far more sophisticated in how various cues are blended into decisions, but it still depends on those received cues. Just like those Bertholdia trigona tiger moths, our anti-drone technologies need to determine those clues used by AI-controlled drones to counter them. Alternatively, we can simply become better at blasting them to smithereens or, as James suggested, fry their circuits. AI-controlled drones are a real challenge, but they are far from invincible.


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18 Responses to How One Moth Species Can Jam Bats’ Sonar Systems

  1. F&L says:

    The day after the 80th anniversary of the victory in the battle of Stalingrad (renamed Volgograd). No moths were available for comment. Luckily the RF Presidential elections are fast approaching next month and the people can hold their government accountable.
    Remember how America elected Donald Trump in 2016 so that the southern border problems could be remedied and everything was patched up in a jiffy.

    Moment Ukrainian kamikaze drone hits massive oil refinery in Volgograd in first airstrike on Russian city since Hitler 81 years ago.

  2. leith says:

    I’m wondering if the MV Behshad, the Iranian ship-spotter for the Houthis, was just targeted with sonar. She turned her AIS transponder back on and is hightailing wards the Chinese Naval Base in Djibouthi.

  3. James says:


    To give credit where credit is due – it was Eric Newhill who suggested frying their circuits. I had not even thought of it until he mentioned it.

    Messing with the cues that the models are looking for makes a lot of sense … but the people training the models can train the models to try and overcome that. Unless a ‘newer, younger TTG’ manages to get hold of their training data of course.

  4. scott s. says:

    There has long been countermeasures to provide false target information or interfere with acoustic guided torpedoes and detection systems from the primitive towed noisemakers to more sophisticated devices like Nixie. A problem of sonar is that sound propagation in water is more strongly impacted by the environment than EM signals in the atmosphere. We have what’s called XBT (eXpendable BathyThermograph) to analyze the relationship of sound velocity to water depth. Biological factors are also at play in certain areas (things like snapping shrimp).

  5. jim.. says:

    A Bat Flew in our kitchen on a warm summers nite once..while my wife and I were doing dishes….He Flew Back and forth ..diving toward our Heads…My Wife screamed..dropped to the floor and Grabbed me around the legs…So…I reached into the Dish Rack…grabbed the fring Pan…And Knocked him Right Out…

    When He came to…He apologized…and I Let Him Go..True Story..

    • TTG says:


      On a family vacation, we stayed in a hunting/fishing camp cabin on the north end of Moosehead Lake. The bottom floor must have had half a dozen stuffed moose heads hanging on the wall. My brothers and I slept in sleeping bags on the floor under the moose heads. I woke up in the dark and heard a lot of fluttering above me. I grabbed my fly rod and just whipped it blindly and a bat fell to the floor right in front of my dog’s nose. I finally grabbed a flashlight and saw the moose heads were crawling with bats. They were gone by morning, so we just enjoyed the rest of the week and ignored the bats at night.

  6. Christian J Chuba says:

    ‘Blurring the image’, does the moth’s defense mechanism require a cluster of moths to create blur? It’s hard for me to see how a moth by itself can confuse the bat as it is the source of the clicking. That is why I am thinking it requires a cluster of moths to cooperate.
    Now regarding drones, I heard a U.S. military guy say that we have acoustic listening stations to detect drones. This would be a purely passive system and not subject to jamming. The only counter measure here is quieter drones, or decoy sounds. Perhaps a cluster of drones would make it difficult to identify a single target as well.

    BTW the Russians have ‘ 1B75 Penicillin’. An acoustic targeting system to direct counter-battery fire. It listens for nearby artillery shells. It either works great or not at all depending on which news releases you choose to believe.

    • TTG says:

      Christian J Chuba,

      Experiments showed the defense mechanism of a single moth was effective against a single bat. But it would be interesting to examine what a cluster of clicking moths would do to a swarm of bats.

      Sound ranging for counter battery fire was developed in WWI.

      • Christian J Chuba says:

        I can now see how a single moth can confuse the bat.
        Let’s say that the bat sends out 100 clicks, it expects to read them back in that order. BTW the bat has potentially much better depth perception than us eyesight creatures. Anyway, if the moth sends back an extra 100 and the bat cannot tell them apart, that would make it blurry.
        Point about drones being that militaries are using passive acoustic listening, so the problem domain is different from a bat using active sonar. So how quiet can you make a drone?

  7. Christian J Chuba says:

    “AI-controlled drones are a real challenge, but they are far from invincible.”

    Does anyone have that yet? I see this as what we called in the corporate world ‘disruptive technology’. If version 1 isn’t invincible, just wait for version 2, 3, 4 etc. It will become close to invincible. The advantage to AI controlled drones is the potential for evasive behavior which I believe you were hinting at and in severing the data link to a remote operator. An AI drone should be fire and forget. Just launch it in the general direction and then let it use on board optics to identify the final target.

    • TTG says:

      Christian J Chuba,

      AI-controlled anti-drones are already in development in Ukraine and probably elsewhere. Like in all other weapons, it will be a constant battle between technologies and counter-technologies.

  8. jim.. says:

    Looks like a Reddish Coating on the Moths Wings,,,and along the top of his Back..
    .Maybe …Its Just Poisonous,,,so Bats dont eat it…That Happens alot..many Cloaks.
    not Clicks.,, perhaps…

    • TTG says:


      Some varieties of those moths are poisonous or just bad tasting. That is their defense mechanism. This particular species is neither. They’ve developed a different defense mechanism.

      • jim.. says:

        Yes…There is a Moth Caterpillar in Costa Rica That has been researched and the Spines Tested for Toxic Reactions to Humans…The fuzzy Spines are brushed along the Researchers Arm and Cause Large Welts all over…and Digestive problems…

        These Moths have Migrated…and since This Tiger Moth..with
        its Fuzzy Only In Arizona.
        .it may actually have Been
        able to carry poisonous spines along its back…like the
        moth catipiller in Costa Rica..or Cloak itself to look Poisionous.

        The are 160,000 species of Moths..Looking at Images…Many Cloak thier wings to Represent Large Eyes Looking Back at a
        Diner…or use many other Disguises…Cloaks…to hide..
        Adapt and Survive..
        Can You Cloak Missles…and Drones..???

  9. Keith Harbaugh says:

    A while ago there was a discussion of U.S. efforts to produce semiconductor chips in the U.S., in New York state I believe.
    I don’t know how that went, but another such effort didn’t work out well.


    LOTS of problems arose, e.g.
    “There is literally not enough qualified workforce in the US to even complete the plant construction,
    and we can leave to the imagination what will happen when the production eventually takes place in the future.”

    And there were other issues.

    • TTG says:

      Keith Harbaugh,

      Global Foundries’ Fab 8 is still going strong in Saratoga, NY. Part of the draw is all the tech universities in the area. Even the secondary education system in that area is top notch. Last year Fab 8 became a major supplier to the DoD.

  10. Mark Logan says:

    I’ve never been able to get my brain wrapped around the phenomena of the electric eel. An aquatic creature developed a 400 volt battery for it’s taser defense mechanism? I’d of lost the bet on that one.

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