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Tales From the Dark Side--of Nature

Entomologist Brian Brown's morbid fascination with ant-decapitating flies covers all aspects of the parasitic predators: the good, the bad--and the very gory.

October 25, 2000|DENNIS ARP | SPECIAL TO THE TIMES

Like all tales of the macabre, this one begins innocently enough. Just a boy and his butterfly net. As a child, Brian Brown chased brightly colored insects near his home in Toronto. Little did he know that he would one day stand eyeball-to-compound-eyeball with the dark side of nature. And love it.

These days, as a mild-mannered but world-renowned entomologist at the Natural History Museum of Los Angeles County, Brown dedicates his professional life to unearthing the secrets of Diptera:Phoridae. More specifically, those of the genus Apocephalus. That's right, he's a fly guy. But these aren't just any flies. The ones Brown studies are unlike anything that's likely to get caught between the window and the screen at your house. These are parasitic predators that are among the few fly species deemed worthy of a common name. It's a name they've earned. They are (cue the ominous organ music) ant-decapitating flies.

These insidious little creatures get their name from the way they reproduce. (Warning: The following description may be too intense for young children or anyone reading this over breakfast. Remember what happened to John Hurt's character in "Alien"? This scene makes that one seem like a bad case of heartburn.)

The female fly isolates a target, then strikes from above. She pierces the ant with her swordlike ovipositor and jams in a single egg, usually at the back of the neck. When the egg hatches, the larva immediately begins eating the ant's head from the inside out. "In Costa Rica, we've found leaf-cutter ants wandering along trails beside their nest mates even though there's nothing inside their heads but a mature, fat phorid fly maggot," Brown said with a slight hint of relish.

Eventually, the ant's head drops off, and sometimes the ant still marches on.

"As parasitoids," Brown said, "these flies are pretty spectacular." As Brown talks, it becomes clear he's in awe of a creature whose head is about the size of the period at the end of this sentence. Ant-decapitating flies have drawn him to field study projects from the equatorial rain forest to the Arctic Circle. The collection he oversees at the Natural History Museum is far and away the largest in the world. He touts the fly's diversity and lauds its survival skills. He even casts it as a hero in the fight against invading fire ants that plague large areas of the Southeast and Southwest, as well as pockets of Southern California.

Brown's research has helped show that the flies are particular in the ants they attack, so natives aren't threatened. Last summer, the U.S. Department of Agriculture released tens of thousands of ant-decapitating flies in Texas, where livestock and pets have been killed by venomous ants accidentally introduced on plants imported from Brazil and Argentina. The flies can't lay enough eggs to kill off a whole colony of ants, but they can pester the insects so much that the ants all but quit looking for food.

One breed of phorid fly attacks the Argentine ants invading many Southern California homes these days in search of water. If the fire ant project succeeds, said Brown, the unwanted Argentines may be targeted next. Until then, he suggests washing away the unwanted visitors with soapy water. The soap breaks down the ants' defenses and they drown. If that doesn't work, there's always Brown's method: patience. "They usually aren't a lasting problem," he said.

Although Brown's affinity for bugs dates to his childhood, he abandoned them as a teen because of the social stigma. (He used the clinical term: "The nerdy geek sort of thing.")

"I discovered girls and played in a heavy-metal band, and the insects went right out the window," said Brown, 39. He rediscovered insects 17 years ago at the University of Guelph in Ontario, thanks to a particularly inspiring teacher who suggested focusing on flies "because almost no one else was."

Brown stuck with flies through his doctoral work at the University of Alberta, where his interest in phorids even grew on his then wife-to-be. "I think they're wonderful things," said Victoria Brown, who works in the Natural History Museum's publications department. "Brian can be really captivating when he talks about them. I like to listen to him. He tells the ant-decapitating part so matter-of-factly."

Brown came to the Natural History Museum from the Smithsonian eight years ago because it offered him the best chance to continue his research. He often shows off his flies to visiting groups, with schoolkids getting a particular kick out of the gory details.

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