Sneaky Smaller Weevils Get the Girl Too

Imagine you're at a bar, chatting up the prettiest girl in the room, when some big meat-head taps you on the shoulder. "That's MY girl," he says, and proceeds to sock you in the face. You defend yourself, successfully fending off this aggressive opponent, but when you turn back around the girl is gone. A tinier guy has managed to sweep her off her feet while you were distracted and now they're arm-in-arm and heading out the door.

That's a PG version of a day in the life of the New Zealand giraffe weevil (Lasiorynchus barbicornis), an unusual looking beetle that uses its remarkably long snout, or rostrum, to drill holes into trees or wage war.

Female weevils use their rostrum to lay eggs inside the trunks of dead trees. However, males, with their longer and nearly club-like rostrum, appear to only use them to battle amongst one another for mates. This creates a society in which bigger is better - the larger rostrum usually winning the joust.

However, some weevil males are smaller than most, and prefer sneaking around over waging open battle. As two dominant weevils fight over the right to mate with a female, smaller males often take the prize while the fighters are distracted.

Similar behavior can be seen among elephant seals, where smaller males have to sneak in some short one-on-one time with the females when the dominant male - called the beach master - isn't looking. This ensures genetic variation among the seal population, even if the beach master still births the most children.

However, while elephant seals barely get by with such a strategy, Christina Painting at the University of Auckland in New Zealand was surprised to find that sneaky weevils have mastered it, reproducing just as much as fighting males.

Painting recently spent a great deal of time monitoring the lives of 79 weevils to reach this conclusion, and has since published her work in the journal Behavioral Ecology.

She calls this sneaky male success a prime example of "alternative mating tactics," and admitted to New Scientist that it was entertaining to witness.

"When the larger male did then try to copulate and there was someone already in the way, that was quite confusing for the larger male," she said.

The researcher adds that with sneaky males being just as successful as the fighters, it now raises the question as to why some males remain so much better equipped for battle.

"It's very hard to explain how something as insane as a long rostrum has evolved if there's no difference in mating success across size classes," she said. "So we certainly imagine that the story is bigger than what we've revealed so far."