July 20, 2017
Fireflies: They’re essential to a perfect July evening here in Ohio. Their gentle flashing brings back memories of childhood adventures and signifies the arrival of midsummer.
Fireflies, or lightning bugs, are more than just pretty lights, though. For instance, did you know that adult fireflies live for only a few weeks? Or that they have important implications for medicine and science? This week, we bring you 10 things you might not know about fireflies.
1. There are over 2,000 species of fireflies in the world. Here in Cuyahoga Valley National Park, look for the common eastern firefly, or big dipper firefly, named for its tendency to fly in a J-shaped pattern. There are about two dozen species total in Ohio.
2. Fireflies flash to attract mates. Three chemicals— luciferase, luciferin, and ATP—work together to produce the firefly’s characteristic glow. Each species has a unique flashing pattern, which the males use to advertise their availability to nearby females. When a female sees a mate she likes, she’ll flash in response, steadily guiding the male to her location. In some species, though, females mimic other species’ flashing patterns to lure unsuspecting males and then eat them!
3. Fireflies are super-efficient producers of light. Unlike incandescent bulbs, which give off heat in addition to light, fireflies produce “cold light.” That means they don’t produce any heat, and 100% of the energy is emitted as light.
4. You’re most likely to see fireflies just after dusk. Head out to CVNP about 40 minutes after sunset, especially in the bottomland forests near the Cuyahoga River. Certain species have very specific locations or times of night when they flash. On warm nights, it’s possible to see fireflies flashing all night long.
5. Adult fireflies live for only a few weeks. The larvae live for about a year, but when they become true winged adults, they survive just long enough to mate and lay eggs for the next generation. Most adult fireflies don’t even eat, focusing all of their energy on finding a mate.
6. Fireflies aren’t very tasty. Fireflies contain bitter chemicals that make them unpleasant to eat or even poisonous to some animals. When threatened, they shed drops of blood to warn off predators, called “reflex bleeding.”
7. You can find fireflies on almost every continent (except Antarctica). They love warm, humid habitat with plenty of woodlands and access to water—making CVNP a perfect home!
8. Fireflies have many other names, including lightning bugs, golden sparklers, blinkies, and moon bugs.
9. Fireflies are useful in medicine and science. When the chemicals found in a firefly’s tail are injected into diseased cells, they can detect cellular changes that can be used to study diseases like cancer. Firefly-specific chemicals have also been used to detect food spoilage, bacterial contamination, or even life in outer space.
10. Fireflies may be disappearing. Light pollution near cities may play a role in decreasing firefly populations, as bright lights from buildings and cars confuse their mating rituals, which rely so heavily on light. Pesticides and habitat destruction may also play a role, as fireflies need plenty of marshy areas and standing water to survive. You can help by turning off outside lights, letting your grass grow a bit higher, and leaving logs on the ground.
Interested in doing citizen science in the name of fireflies? Check out Firefly Watch, an ongoing firefly observation project managed by the Museum of Science in Boston.