  Far above the floor of the Chilean rain forest, two giants of the insect world prepare to engage in battle. With six spindly legs braced against the tree limb, each of the combatants rears up and flaunts its massive, curving mandibles. Longer than the head, thorax and abdomen combined, these exaggerated weapons are tailor-made for grappling their fellow stag beetles.
The two males lunge forward and lock mandibles, each thrusting and shifting position so as to secure a solid grip on his adversary. The winner will remain in the high treetops to mate with a female, while the loser plummets to the forest floor. Given the ferocity of this insect competition captured by Life, is there any wonder we call this particular species "Darwin's beetle?"
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Watch a "Darwin's Beetle Toss Rivals"
BATTLE IN THE TREETOPS
In the Japanese sport of sumo, one grappler becomes the victor when he or she forces the opponent outside a circular ring. For Darwin's beetles, the rules are much the same. Only instead of merely powering their rival out of bounds, they strive to throw them out of the tree itself. As "
Insects" episode producer Rupert Barrington explained, breeding rights — not bragging rights — are at stake for the beetles.
"That's how they win their fights," Barrington said. "You have to get the other beetles out of the trees in order to clear the area of rivals."
In order to achieve this, the male beetle uses his giant mandibles. Yet as powerful as they look, they're meant only to grip rivals, not break them in half.
"The pinchers are not particularly strong, but they're curved to provide a kind of wrestling grip," Barrington said. "The pinchers kind of curve out on either side to accommodate the body, and they have a little hook underneath. Once they get those pinchers over the other beetle's body, the hook just fits perfectly under the wingcases to give him a grip. And then that male can heave the other off the branch."
Once a male has cleared the treetops of rival suitors, he finally has his shot at mating with one of the females in the upper branches. In order to mate with her, however, he has to catch her.
"The females we filmed weren't particularly receptive to the males," Barrington said. "So the male had to chase after her, and it's quite interesting to watch. If he can catch up with a female, he'll stand over her and trap her. He makes a kind of cage out of his legs, and these huge jaws come over the front and then she seems to become compliant."
The jaws of the male Darwin's beetle are not made for snuggling, however. Once the mating is over, he releases his grip by simply throwing the female out of the tree. Whether this behavior serves a purpose or is just a byproduct of the male's pent-up fighting instinct, scientists can't say for sure.
"It makes good sense in a way because she lays her eggs in amongst the grass down on the ground," Barrington said. "So it's a kind of short way down. Whether that's biologically the reason or whether he's just so full of testosterone after fighting he just can't help himself, we don't know."
Either way, all those females and defeated males are far from doomed.
"Insects are generally very tough because they have a very hardened external skeleton, and these beetles are very tough," Barrington said. "Because they're so light, they don't fall at any great rate, and when they land they just seem to bounce and pick themselves up and head back up the tree again."
Continue: Filming Darwin's Beetles
