Birds and bees have nothing on ants

Posted: May 05, 2012

For those who think spring is all about robins arriving, window cleaning, or crocuses budding, I have two words for you: ant sex.

Now, I know what you’re thinking: Those tiny black creatures marching relentlessly toward the sugar bowl are all infertile females who have no interest in sex. This is true. But when the days lengthen and the earth warms, the thoughts of a select class of ants turn to passion.

An ant queen produces all the ants in a colony. The vast majority are sterile female workers. But at certain times of the year, she also produces males, as well as some females capable of laying eggs themselves. These future queens and their mates have a startling characteristic not shared by other ants in the colony.

People sometimes talk about being transported on the wings of love. For fertile ants, this is a literal concept. They have a pair of transparent wings on their backs, ready to bear them up out of the gloomy passages of the nest and into the soft spring air.

In some ant species, both sexes fly. In others, only the males do, while the would-be queens have to crawl out of the nest and send out pheromones to the more widely ranging males.

The flying forms of ants are called alates, after the Latin word for wing, though the wings will be used for only the briefest of times.

I imagine the alates underground before liftoff, as nervous as any cast member backstage on opening night, fidgeting and rustling their paper-crisp wings. The so-called nuptial flights are doomed in wet or windy weather. But if the conditions are right, the alates — thousands upon thousands of them — rise in clouds, flying away from the nest in search of aerial romance.

Of course, for the bulk of the alates, romance proves elusive. They are eaten by predators or fail to find a mate. (On the bright side, alate emergences are a bonanza for birds.) If two ants do manage to connect, the much-smaller male attaches himself to the female and inseminates her, whereupon his genitalia explode and he falls to the ground lifeless. I tell my students that this is the best possible outcome for the male, evolutionarily speaking, but they seem skeptical.

The males vie with each other for access to the virgin queens, and they can be extremely determined. The Internet was abuzz recently over a video that ant expert Alex Wild posted on his blog and succinctly headlined: “Male ants don’t particularly care if their mate is dead and being eaten by a spider.” As Wild noted — and who could argue? — “I can’t imagine anything more unpleasant than being sucked dry by a crab spider latched to my skull. Other than the same, but simultaneously being assaulted by a sex-crazed drone swarm.”

The swarms sometimes form enormous masses. In 2009, flying ants were so numerous that they interrupted a championship cricket match in South Africa. The alates from multiple colonies often emerge at once, which helps reduce inbreeding. This probably happens because they all respond to the same environmental stimuli.

Ant sex reminds us that spring can be scary, or at least sobering, particularly for non-humans — millions of ants, millions of robin eggs, millions of flower seeds, most destined to die before they are grown, and almost all unlikely to reproduce. All that rampant profligacy; all that heedless destruction. In Pilgrim at Tinker Creek, Annie Dillard writes, “I can like it and call it birth and regeneration, or I can play the devil’s advocate and call it rank fecundity — and say that it’s hell that’s a-poppin.’ ”

I don’t know if it is hell exactly; if so, the netherworld bears a striking resemblance to, well, any place with a seasonal climate. Regardless, the swirling multitudes of winged ants remind us that spring may be about renewal, but it’s also about going for broke, about massive overproduction, and about one sliver of time when even the most earthbound creatures can break loose and head for the sky.

Marlene Zuk is a professor of ecology, evolution, and behavior at the University of Minnesota. Her latest book is “Sex on Six Legs: Lessons on Life, Love, and Language From the Insect World.” She wrote this for the Los Angeles Times.

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