Killer beetle larva attaches itself to its much larger amphibious victim.
The unexpected diet of the ground beetle larvae includes frogs several times larger than the meager youngsters. The beetle larvae stick to frogs and suck the life right out of them. Gil Wizen/AFTAU

It's a dog-eat-dog world out there, or in some cases, a beetle-eat-frog world.

The unexpected diet of the ground beetle larvae includes frogs several times larger than the meager youngsters. The beetle larvae stick to frogs and suck the life right out of them.

How the squirmy larvae get their gigantic feeding payday involves some clever trickery: the predator beetle larvae pretends to become victim to the frog, when really the amphibian becomes the hapless victim.

It's really a predator-prey role reversal - the insect actually draws in its potential predator instead of avoiding it, said Gil Wizen, lead author and entomology Ph.D. student at the University of Toronto. It's quite a unique phenomenon.

Adult beetles have their own kill method, an ambush followed by paralyzing the frogs by making a small incision in the amphibious backs, either severing the spinal cord or cutting a muscle the frog needs to jump away.

The beetle larvae are no gentler.

The researchers found that the squishy larvae perform dance-like movements to taunt the frogs into trying to eat them. The larvae open their jaws and move their antennae from side to side trying to get the interest of a frog.

No worries to the larvae, however, for researchers found when the frog tried to grab the larvae with its tongue, the youngster jumped and attached itself to the amphibian.

Then, the slow feast begins. In the early phases of development, the larvae will start to suck the fluid out of the amphibian's body and will eventually moult and leave a scar on the frog's body.

More mature larvae become deadly as they chew away at the amphibians leaving nothing but a heap of bones.

The story behind the killer beetle isn't just a ghastly reminder of how the food cycle works.

This study started as a side-study while checking the population status of toads in the coastal plain of Israel, said Wizen who worked on the research in the lab of Avital Gasith at Tel-Aviv University. The phenomenon was first discovered in 2005 by Eldad Elron and Alex Shlagman.

In Israel there are only six amphibian species and all of them are threatened by extinction, he said.

The research was published Sept. 21 in the online edition of PLoS ONE.

Prey