Here is a fun animal story I recently read about in the New Scientist (September 2024).
In China, a study has shown that an orb-weaver spider appears to use firefly light to lure more firefly prey into its web. Male fireflies have a habit of getting tangled in the orb-weaver’s web. During normal courtship, female fireflies use a single light flash to attract a potential male mate to their location, whereas the male flashes twice to attract a female.
However, some of the male fireflies trapped in orb-weaver nets flash only once and more males were trapped in these nets.
Scientists wondered if the spiders manipulated the trapped male firefly to attract more males into the web as spider prey. So, they set up an experiment to study 161 webs.
Some webs had a spider present and others did not. Some of the nets with spiders had a trapped normal male firefly whereas other nets had a trapped male firefly but the ‘flasher’ on the abdomen was blacked out with ink (i.e. he was a ‘non-flasher’).
Observations: Webs with spiders and single-trapped male fireflies attracted more fireflies to the web than webs with no spider or ones with non-flashing male fireflies. Also, the immobilized male fireflies trapped in spider-occupied webs seemed to have an unusual flash signal that looked more like the normal, single female flash.
Males trapped in webs lacking a spider had their normal double flash. This suggested that perhaps the spiders were manipulating the male fireflies signal to mimic those of a female and hence luring in males looking for a mate.
How the spiders change the trapped male’s flashing pattern is not known. One possibility is the spider’s venom or a bite itself causes a change in the male firefly’s signal. Regardless, these orb-weaver spiders are not simply passive trappers.
The photo is a common orb-weaver spider found in Northwest (not the Chinese one described above).