Finding a mate can be hard. Take the case of fireflies in many areas of the world. In the dark of night, they call to potential mates using the glowing chemical lamp in their abdomen. In one species of tropical Asian firefly, both males and females flash their signals into the darkness. Females have just one lantern in their abdomen and flash in slow single pulses. Males flash in quick succession from two abdominal lanterns. In 2024 an international team of biologists reported their finding that sometimes, instead of love, a fiendish trap may await these male fireflies summoned by what seems to be the flash pattern of a female.
The scientists were studying a species of garden spider found in China that spins its web at night. The researchers found some of these webs were full of trapped male fireflies. Why did the spider catch so many male fireflies? The researchers found that when a male firefly was trapped in the web, the spider wrapped it in silk and injected it with paralyzing venom, much as it would any other prey.
But, while the spider often kills and eats other victims right away, it leaves trapped male fireflies. The trapped fireflies continue to flash, but now with slow single pulses more like the female’s. The trapped firefly is transformed into a living lure, drawing other male fireflies to their doom. What causes the transformation? The researchers think that the changed flashing pattern may be due partially to stress, but mostly due to either the spider’s venom or the patterns of its bites. Further experiments will be needed to learn more.
A special thanks goes to Carlos R. Cordero, Autonomous National University of Mexico, for reviewing this episode!
Further Reading
- This spider uses trapped fireflies to lure more prey Science News
- These spiders use captured fireflies as flashing lures to snare more prey Smithsonian Magazine
- Spider exploits firefly’s flashing signal to lure more prey Phys.org
- Spiders force male fireflies to flash like females—luring more males to their death Science
- Spiders may lure male fireflies to their death with a call of love National Geographic
Fu et al. 2024. Spiders manipulate and exploit the bioluminescent signals of fireflies, Current Biology, 34, R747-R771.