Fireflies use flashing lights to communicate with each other through lantern-like organs on their bodies. In the species Abscondita terminalis, male fireflies produce multi-pulse flashes from their two lanterns to attract females, while females respond with single-pulse flashes from their single lantern to draw in males. Recently, researchers published evidence in the journal Current Biology on August 19, showing that the orb-weaving spider (Araneus ventricosus) takes advantage of these flashing signals. It manipulates the flashes of male fireflies caught in its web to imitate female signals, enticing other male fireflies to become its next meal.
Fireflies use flashing lights to communicate with each other through lantern-like organs on their bodies. In the species Abscondita terminalis, male fireflies produce multi-pulse flashes from their two lanterns to attract females, while females respond with single-pulse flashes from their single lantern to draw in males. Recently, researchers published evidence in the journal Current Biology on August 19, showing that the orb-weaving spider (Araneus ventricosus) takes advantage of these flashing signals. It manipulates the flashes of male fireflies caught in its web to imitate female signals, enticing other male fireflies to become its next meal.
According to extensive field research, the study’s authors suggest that Araneus ventricosus engages in deceptive communication by first trapping male fireflies in its web and then causing them to emit bioluminescent signals that differ from the typical male-attracting signals of A. terminalis males. Instead, they mimic the signals usually made by females, which results in the entrapped male fireflies luring even more males into the web, becoming prey for the spider.
This discovery originated when Xinhua Fu, the study’s lead author from Huazhong Agricultural University in China, observed numerous male fireflies caught in the webs of orb-weaving spiders during field studies. Curiously, female fireflies were seldom, if ever, seen in these webs, even during follow-up visits where the pattern continued.
Fu speculated that the spiders might have a method to draw in male fireflies by altering their flashing behaviors. Behavioral ecologists Daiqin Li and Shichang Zhang from Hubei University, along with Fu, conducted field experiments to observe both the spiders’ and the fireflies’ actions. Their findings showed that webs were more effective at capturing male fireflies in the presence of spiders than in their absence.
Upon further investigation, they discovered that the signals produced by male fireflies caught in spider webs resembled those of free females. Specifically, the trapped males emitted single-pulse signals using only one lantern instead of both. These male fireflies did not attract additional males when alone in the web.
The results implied that the males weren’t changing their flashing as a signal of distress. The researchers speculate that it’s the spiders that modify the fireflies’ signals.
“While orb-web spiders typically have limited ability to see spatially, they rely more on timing to differentiate flash signals,” Li explained. “When they detect the glowing signals of trapped male fireflies, the spider employs a special method for handling prey that includes repeated wrap-and-bite maneuvers.”
The study demonstrates how animals can utilize indirect but effective signaling to target specific types of prey. The researchers suggest that there may be numerous unexplored examples in nature where predators use mimicry to influence the behaviors of their prey through various forms of communication, such as sounds, pheromones, or other methods. They emphasize that further research is necessary to determine whether the spider’s venom or the bites themselves cause changes in the flashing patterns of the trapped males.
This research was funded by the National Natural Science Foundation of China, the National Key R&D Program of China, the Singapore Ministry of Education Academic Research Fund, and the Slovenian Research and Innovation Agency.
