Forgive me, gentle reader. I forgot to post this gruesome tale for Halloween. I didn’t want you to miss this horrific story, so here you are, only a few days late…

In a surprising reversal of fortune, Israeli researchers have found a certain group of beetle larvae that feed on frogs.

As Ed Yong reports in his Discover blog:

During its lifetime, a frog will snap up thousands of insects with its sticky, extendable tongue. But if it tries to eat an Epomis beetle, it’s more likely to become a meal than to get one.

The larvae have shown 100% success in their ability to lure the frogs into becoming a meal. In fact, these beetles eat nothing else in the larval stage. Here are the gruesome details.

According to the researchers, Epomis larvae combine a sit-and-wait strategy with unique movements of their antennae and mouthparts to draw the attention of an amphibian (frogs and toads were used in the study). Thinking it has spotted potential prey, the amphibian comes closer and the larva increases the intensity of these enticing motions.

When the amphibian attacks, the larva manages to avoid the predator's tongue and uses its unique double-hooked mouthparts to attach itself to the amphibian's body and initiate feeding, which can include both sucking of bodily fluids and chewing body tissues, usually killing the much larger amphibian.

“It seems that instead of serving as food items for amphibians, Epomis larvae have evolved to specifically take advantage of amphibians as a food source,” says researcher Gil Wizen.

These findings extend the perspective of co-evolution in the arms race between predator and prey and suggest that counterattack defense behavior has evolved into predator-prey role reversal.

The research is published in the online journal PLoS ONE. Images and video of the beetle and the frightening attack can be found at Wired and Discover.

Image: Gil Wizen/AFTAU

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