Got Fireflies? Try Talking To Them With A Green LED

[ChrisMentrek] shares a design for a simple green LED signal light intended for experiments in “talking” to fireflies. The device uses simple components like PVC piping and connectors to make something that resembles a signal flashlight with a momentary switch — a device simple enough to make in time for a little weekend experimenting.

Observe and repeat flashing patterns, and see if any fireflies get curious enough to investigate.

Did you know that fireflies, a type of beetle whose lower abdomen can light up thanks to a chemical reaction, flash in patterns? Many creatures, fireflies included, are quite curious under the right circumstances. The idea is to observe some fireflies and attempt to flash the same patterns (or different ones!) with a green LED to see if any come and investigate.

[ChrisMentrek] recommends using a green LED that outputs 565 nm, because that is very close to the colors emitted by most fireflies in North America. There’s also a handy link about firefly flashing patterns from the Massachusetts Audubon society’s Firefly Watch program, which is a great resource for budding scientists.

If staying up and learning more about nocturnal nightlife is your thing, then in between trying to talk to fireflies we recommend listening for bats as another fun activity, although it requires a bit more than just a green LED. Intrigued? Good news, because we can tell you all about the different kinds of bat detectors and what you can expect from them.

25 thoughts on “Got Fireflies? Try Talking To Them With A Green LED

  1. Last month during a thunderstorm in the distance, I noticed the fireflies flying higher than usual in the direction of the storm. I suspect the lightning 🌩 flashes were close to their signal pattern.

    1. What are you even talking about? it’s a push button, a rocker switch, a battery and a led, what programming?

      Oh and Python is a cardinal sin, don’t even get me started on how all the overhyped bs “AI” lately is all made with Python lmao, fits extremely well.

  2. There was a Kickstarter for a more complex firefly caller ( ) about 7 years ago. Sadly there are no fireflies where I live now and most are gone where I grew up.

  3. This is an extraordinarily BAD idea. Fireflies are disappearing all over the globe due to habitat loss and too many artificial lights interfering with their mating patterns. Now this device will no doubt make it just a little harder for them find a mate and make new fireflies.

    Biology and ecology ought to be mandatory courses at every grade level.

      1. This LED? Nah. But the fact that people aren’t tearing the whole world apart to figure out why the number of insects have been utterly decimated since the 1970s is shocking; that’s a very serious issue. Humans seem to be more fond of blasting the night with artificial light and atrazine-soaked snacks than life itself

  4. Chris Mentrek is not talking ‘specimen collection’ which is common with biologists, but rather is demonstrating a technique for budding scientists to become involved with the firefly in a natural habitat such as a backyard. In researching one aspect of the firefly, a small number of the citizen scientists may become interested in the declining numbers of the insects and decide to further study.

    Getting new people engaged in science is a great endeavor and may yield solutions to current and future problems.

  5. Fireflies (glowbugs) are pretty much gone from the UK and northern Europe now – they used to be very common, if you walked the country roads at night you’d see hundreds. Light pollution seems to have killed them all off, not seen one in the south of the UK for over a decade now and the first time I spotted one in Europe was in Croatia, and it was only a couple for over 2km of walking. Light pollution is a real pain in the ass.

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