The Best American Science and Nature Writing 2014 (34 page)

In a country of more than 313 million, a couple hundred infections doesn't sound like a lot—and it's not. But you need only take a look across the Atlantic to find out how quickly measles can spread out of control. In 2007 there were just forty-four infections in France, a country where vaccination is recommended but not required. Over the next four years, more than twenty thousand additional cases were recorded. Nearly five thousand of these patients required hospitalization, and ten of them died.

As the containment efforts illustrate, the fact that there haven't been any recent deaths in the United States doesn't mean measles isn't having a real impact on the economy or on public health. One of the reasons Madoff oversaw an effort in Massachusetts to contact everyone who might have been exposed was to make sure they were OK. Another was to identify anyone who wasn't vaccinated so they could “isolate themselves and be out of work and out of school.”

The state isn't releasing estimates for the total cost of these two infections, but a 2010 study in
Pediatrics
quantified the expense of containing a 2008 outbreak in San Diego in which 11 children were infected—and another 839 people were exposed. That cost the public sector $124,517, an average of more than $10,000 per infection. These are costs borne by all of us: every tax dollar spent containing measles is a dollar not spent on other public health initiatives.

Maybe you're not particularly civic-minded. If so, consider this: forty-eight children too young to be vaccinated in San Diego had to be quarantined, at an average cost of $775 per family. Another infant had to be hospitalized after being infected—a harrowing ordeal for that child's parents and one that rang up almost $15,000 in medical costs.

All of this is worth remembering the next time parents who don't vaccinate their children tell you they're making a purely personal choice. This is, of course, technically true, in the same sense that driving after having a few beers is a personal choice. As the mother of the ten-month-old hospitalized in San Diego said, if people want to make that choice, they should go live on an island with its own schools and doctors: “their own little infectious disease island.”

FROM
Nautilus

 

F
IVE WORLD WAR II
bombers took off from a Florida airfield on October 5, 1967, to bomb the American South. An article that ran that morning in the Sarasota
Herald-Tribune
said that three B-17s and two PV-2s laden with 10,000 pounds of death-dealing cargo each would carry out their missions “with the City of Sarasota and eastern Manatee as their targets.”

While the bombers were certainly at war, they weren't dropping explosives. Their enemy was a millimeters-long, brownish-red insect known to scientists as
Solenopsis invicta
, meaning “invincible ant,” and known to lay people as fire ants, aka “ants from hell” and “them devils.” The bombers were to unload mirex, a poison usually applied to grits, onto the critter.

By the late 1960s, the fire ant had been in the American South for more than thirty years. Southerners spoke of ruined crops, destroyed wildlife, and the ants' fiery sting. How much damage the ants had actually caused was uncertain, but it was enough for the U.S. Department of Agriculture (USDA) to declare war on the pest. During an eleven-year campaign, more than 143 million pounds of mirex were dropped across 77,220 square miles of land from Texas to Florida, costing close to $200 million.
¹
The outcome? The ants nearly doubled their range. The mirex, which was later found to be a carcinogen, persisted in the environment for decades, accumulating in birds' eggs, mammals' milk, and human tissues. The world's leading ant researcher, E. O. Wilson, dubbed the mirex program the “Vietnam of entomology.”

Today, if you draw a line from Virginia Beach to Nashville to Abilene in west Texas, you'll find fire ants everywhere below it, as well as in Southern California.
²
The ants' annual impact on the economy, environment, and quality of life in the United States totals $6 billion, according to entomologists at Texas A&M University. In Texas alone they rack up $1.2 billion each year: $47 million at golf courses; $64 million at cemeteries (the ants love the open and slightly overgrown habitat around tombs); and as much as $255 million in the cattle industry. They cause other problems too. In Virginia Beach, a thirty-year-old former marine, Bradley Johnson, was stung by fire ants while working outside—and died of anaphylactic shock. On at least one occasion, fire ants invaded an elementary school in Tennessee to get candy stashed in kids' lockers. At Greystone Retirement Community in Huntsville, Alabama, a staffer found seventy-nine-year-old Lucille Devers covered in fire ants, which were crawling from her mouth, nose, ears, and hair: the ants frequently enter nursing homes, attracted by crumbs left in residents' beds.
³
And scientists anticipate that the ants will keep expanding their range. Climate change and crossbreeding with species more tolerant of cold may enable them to settle farther north.

I, on the contrary, moved south. Last August my girlfriend, Karen, and I sold most of our belongings, piled two cats, a terrier, and a pudgy brown Chihuahua named Jazzy-B into a minivan and drove from New York City to New Orleans. A few weeks later, we toasted our arrival with a picnic in City Park. As we rolled up our blanket, our legs suddenly caught fire. Under the glow of a streetlight, we slipped off our pants to find our legs crawling with ants. I received more than two hundred stings, which formed welts the size of drink coasters, and my ears and throat swelled up. Half a dozen Benadryls later I was fine, except for hundreds of very itchy pustules. Luckily I wasn't anaphylactic, but between 0.5 and 5 percent of the U.S. population is.
⁴
For the most allergic, such stings can cause spasms of the bronchial muscles or coronary arteries, preventing oxygen from entering the bloodstream and causing death within minutes. When a few weeks later Jazzy-B stepped on an ant mound and howled, spending the rest of the day licking his paw, I was ready to declare my own war on the fire ant. But first I had to research my enemy.

The range of
Solenopsis invicta
covers a vast wetland in southern Brazil and Paraguay known as the Pantanal. Sometime in the early 1930s the ants stowed away in coffee sacks, soil, or hollow logs piled in the bottom of a cargo ship. The voyagers were probably just a handful of queens, each about the width of a thumbnail. They ate what they could find down in the hold—cockroaches, beetles, sugary cargo, and, when the pickings got slim, themselves, digesting their own wing muscles and fat reserves. Their ship may well have steamed past Rio de Janeiro, the mouth of the Amazon, and the lush peaks of the Antilles, all while their first batch of eggs gestated in their abdomens. In Mobile, Alabama, the ship docked, the sacks or soil or logs were unloaded, and the queens disembarked. Beneath the port's loading cranes and circling seagulls, perhaps in a patch of newly cut grass, the ants established their first colony: a mound of soil honeycombed with chambers and tunnels that ran as much as 4 feet deep. They like to build mounds in disturbed habitats such as the edge of a road, the side of a building, pastures, lawns, or near a busy port.
⁵
They eat pretty much anything—seeds, nectar, worms, weevils, butterflies, and even baby sea turtles, snakes, and alligators—catching the young as they hatch.

Colonies consist of queens, workers, and sexuals, also called alates. Queens lay eggs that hatch into larvae—tiny, white, ricelike kernels that develop into adult ants. Alates are born at the end of winter or the beginning of spring and spend their lives fattening up and preparing for their mating flight. Workers begin life as nurses, grooming and feeding the brood and the queen. They move on to tasks like nest maintenance and sanitation. In their golden years, workers become foragers, handling the colony's most dangerous job, as it exposes them to predators and the elements. As the life in them winds down, workers act as their own pallbearers, lying down to die in a mass ant grave called the refuse pile.

To trace the ants' seemingly unstoppable march through the South, I decided to follow their path from where they first staked their claim to American soil. Just before I left, like an ominous sign from some myrmecological god, a mound swelled up in our backyard. I headed out on my odyssey nonetheless, undaunted.

Mobile, the twelfth largest port in the nation, which last year handled 26 million tons of cargo, greeted me with loading cranes that looked like characters from some gigantic industrial alphabet, a stench of diesel fuel, sea spray that hung in the air, and—sure enough—fire ant mounds. Near the port, cattails poked out the top of one. Its surface was lifeless, but when I kicked it lightly, seeking revenge for my itchy pustules, the creatures swarmed out. They might have been the great-great-great-great-great-great-great-great-great-great-great-grandchildren (queens live about seven years) of the group that had steamed here from South America back in the 1930s.

A short walk from the port was a neighborhood of arching oaks and trim ranch homes with well-clipped lawns. I stopped at 550 Charleston Street, the childhood home of E. O. Wilson—to ponder the fact that the planet's most famous ant biologist grew up at the epicenter of the planet's most famous ant invasion. In the weedy vacant lot next door, a young Wilson studied beetles, butterflies, spiders, and all manner of ants, including
Solenopsis invicta
, whose mound he first discovered in May 1942, at age twelve. “I still remember the species I found, in vivid detail,” Wilson wrote in
Naturalist
, a book about his insect-happy childhood. Now the neighborhood appeared to be fire ant–less—thanks to the tireless, creative, and brutal efforts of its human inhabitants.

Sitting next to a table that held a rifle and a dead squirrel, Lonnie Rayford, a seventy-two-year-old farmer, told me he “done got bit” many a time. In his opinion, one that science does not really confirm, just plain grits were good enough to kill the pests. “Dig a hole and put grits in there, they gonna take it down to the bottom and give it to the queen,” he said. “Them grits will kill them.” Down the street, a husky man pulling weeds from his garden told me he used poison.

From Mobile I headed northeast to Montgomery, where I drove by the state capitol, a creamy white dome calling to mind a magnificent wedding cake. I stopped at Dixie Hardware to learn about fire ant control from the pros. A bearded worker named John showed me to aisle nine, which was an exterminator's nirvana.

“You got roach and ant killer, you got ant killer, you got Ant Max—it's some kind of trap,” he said, holding up a rectangular red-and-yellow box that looked like it could have contained movie theater candies, except for a drawing of a vicious fire ant on the side. The best seller was a big orange bag that read “Spectracide Fire Ant Killer Mound Destroyer.”

John's coworker Richard explained to me the challenges and intricacies of mass insecticide. The problem with poison was that ants often simply moved into the neighbor's yard, requiring neighborhood-wide poisoning efforts—in other words, it took a village to rid itself of the pests. Another trick involved two people shoveling ants from separate mounds into one another—according to Richard, the ants will assassinate the foreign queens. And then there is gasoline, apparently Alabama's preferred eradication method. “Take a broom handle, stick it down the mound, pour gas on it, and I know it's gonna burn whatever is in there,” Richard said excitedly.

Eliminating fire ants seemed a bit like making cornbread: every Southerner had his own favorite recipe. By this time, my welts were long gone and I began to feel bad for the little ants. Especially since I understood that their inexorable spread was, in large part, our own fault.

Naturally, ants don't really spread that fast: during the 1930s and 1940s fire ants migrated out from Mobile at the rate of about 4 to 5 miles a year, a distance thought to be covered mostly in mating flights. On warm days following soaking spring or summer rains, alates exit the mound surrounded by a gang of worker bodyguards and launch into the air to mate—which they do in large clouds called mating swarms. Males inject females with a lifetime supply of sperm and then die. Newly mated queens land, kick off their wings, and scurry away to start new colonies, avoiding predators like dragonflies, which love to gobble their sperm-filled abdomens. Queens typically fly a few miles during mating flights, and if the wind is right, they can fly more than ten. But that's it.

Ants can also move when disturbed. In such a case an entire colony moves, but typically only a few feet, a migration initiated automatically by the workers. And a good many fire ant colonies across the South—known as polygyne colonies, meaning those with more than one queen—can actually move without mating flights, by budding off like yeast. A queen and some workers will simply wander off to start a new colony, but again, they won't go far. The most successful means for fire ant migration, however, is us. Humans.

In 1949 fire ants were mostly situated in a roughly 50-mile-wide radius around Mobile and in a few spots in central Alabama and Mississippi. But as Americans moved to the suburbs during the 1950s, desirous of white picket fences, front lawns, and ornamental shrubs, the nursery trade boomed. Soil, plants, and pots were shipped across states and counties. Hidden in the dirt caked on a bulldozer, in the root ball of a nursery plant, or in the bed of a pickup truck, a newly mated queen can travel hundreds of miles. Thanks to our horticultural aspirations, by 1957
S. invicta
were in every southern state except Kentucky and the Virginias.

It was around then that the U.S. Department of Agriculture set out to eliminate the invaders.
⁶
In 1958 it established a quarantine that restricted the shipment of soil, nursery plants, and baled hay from areas infested with fire ants to those without, unless the products were first treated with insecticides. Between 1957 and 1962 the USDA coated 2.5 million acres with clay granules containing the insecticide heptachlor. It did indeed kill fire ants, but also blackbirds, quail, geese, frogs, dogs, cats, crabs, and millions of fish—a famous fiasco that helped inspire Rachel Carson's
Silent Spring.
Few at the USDA seemed to heed her warning, so the war continued. That entomological Vietnam, which lasted from 1964 to 1975, according to
The Fire Ants
, a book by myrmecologist Walter Tschinkel, left 24 to 33 percent of southerners with mirex in their body tissues.