Deadly Australian Assassin Bugs Rub Themselves in Sticky Resin To Hunt Prey

Humans and primates aren't the only animals to use tools to catch dinner. A bizarre species of bug takes resin from plants, which serves as a kind of glue trap for prey, researchers have discovered.

The assassin bug, native to Australia, uses sticky resin from spinifex grass to capture its prey, slathering itself in the gluey substance, according to a study published in the journal Biology Letters.

Researchers from Macquarie University in Australia found that both male and female assassin bugs would scrape resin off the blades of grass, rubbing it onto parts of their own bodies.

Inside containers, the researchers added some of the bugs' prey. They observed as the bugs attempted to catch and eat them, both with the resin and without it.

They found that after the resin had been removed from the bugs, they were less successful at capturing their prey. They were 26 percent more successful at capturing their prey when the resin was on their bodies. They also found that flies placed in the arena with the assassin bugs were 64 percent more likely to escape after the bugs' resin had been removed.

"Spinifex resin conveyed a predatory advantage to the assassin bugs. This advantage likely derived from the resin's adhesive properties. Prey could still escape after being touched by the assassin bugs, but this was less likely to happen if the assassin bugs were equipped with resin," the authors wrote in the paper.

However, they also found that the resin didn't act like flypaper, permanently disabling the prey. Rather, it slowed down the prey just enough for the assassin bugs to capture them.

"Prey never appeared to be fully stuck to the resinous surface of the assassin bugs. Rather, it appears that brief, temporary adhesion, delayed prey responses sufficiently enough for the assassin bugs to grasp and stab their prey," they wrote.

The researchers concluded that the assassin bugs were using the resin as a tool.

"Gorareduvius sp. can thus be considered a tool-user, and since this behaviour was present in all individuals, including newly hatched nymphs, tool-use can be considered to be stereotyped. Our study, along with others, suggests that, when compared with other insects, tool-use is disproportionately common within the assassin bugs," they wrote in the paper.

This is quite significant in the insect world, as tool use is usually only associated with the most intelligent species of animals. Humans, primates, dolphins, some species of birds like crows and other corvids, and octopuses are known to use tools regularly. Some other insects use tools too, including some wasps, ants, and crickets.

"This makes the study of tool-use in assassin bugs a particularly promising case for understanding the ecological and behavioural conditions that facilitated the otherwise unlikely evolution of tool-use," they wrote.

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