A newly found spider species in the tropical rainforests of Australia has amazed scientists with its unique hunting method that propels prey into the air using a spring-loaded silk trap. The study, recently published in the journal Current Biology, details how this small arachnid constructs a cone-shaped snare to fling green tree ants into its web, earning it the moniker “ballista spider” in reference to ancient Roman projectile weaponry.
Ajay Narendra, a biology professor at Macquarie University in Australia and one of the study’s main researchers, expressed awe at witnessing the spider’s behavior firsthand. The spider, belonging to the Propostira genus, has yet to be formally named as a species.
The initial sighting of the spider was made by researcher Greg Anderson in 2022, who observed a green tree ant being catapulted into a web in a remote rainforest on Queensland’s Cape York Peninsula. This observation prompted a team from Macquarie University to investigate further in 2023, a challenging task given the spider’s elusive nature.
Through the use of high-speed cameras, the team spent 10 days documenting the spiders’ unconventional hunting technique. The swift attacks of the spiders proved difficult to capture on film initially, but the researchers eventually recorded the process. These spiders, which measure between three to five millimeters in length, are nocturnal creatures that hide during the day and emerge at night to construct intricate traps beneath their primary webs.
Using silk tension lines attached to various anchor points, such as leaves or branches, the spiders create a cone-shaped structure that ensnares green tree ants. The struggling ants trigger the trap’s release, launching them into the air and directly into the waiting predator’s web. The researchers found that the green tree ants were specifically attracted to the final silk layer of the trap, hinting at the use of pheromones for targeted lure.
Narendra speculates that this evolutionary strategy allows the spiders to hunt formidable green tree ants without direct confrontation, leveraging the element of surprise and avoiding physical combat. Further research will focus on analyzing the spider silk to determine the presence of pheromones tailored for prey specialization.
Saad Bhamla, an associate professor at the University of Colorado-Boulder’s BioFrontiers Institute, suggests a simpler explanation for the spiders’ targeting of prey, proposing that the aggressive nature of green tree ants prompts them to investigate any nearby structures, including those built by spiders. The rapid launch mechanism employed by the ballista spider subjects the ants to significant G-forces, surpassing those experienced by jet pilots.
Unlike the slingshot spider, which actively launches itself at flying insects, the ballista spider stores energy in its silk trap to propel prey with substantial force while maintaining a safe distance. This discovery underscores the ongoing revelations in nature and the continuous exploration of its wonders that researchers are still unraveling in 2026.
