Invasion of the Ants
Cry for Me, ArgentinaIt is a battle fought daily in homes and businesses across America, but the invaders have grown heady with their success. They have struck at the heart of human defenses. Now they're attacking pest control companies."I can see them outside my window right now," said Jim Batchelor of Batchelor Termite and Pest Control. "It is a very persistent, mind-boggling insect." Ants have had plenty of time to evolve, giving them a substantial head start over humans. The oldest known ant-a specimen preserved in amber-has been dated at 80 million years old. That takes them back to the Mesozoic era, around the time the dinosaurs vanished.Modern humans have walked the earth about 100,000 years. Ants live in nearly every corner of the earth, with the exception of Antarctica, Iceland, Greenland, and a few remote islands.They are the most successful creatures on the planet -- the most numerous family of insect, itself the most numerous class in the animal kingdom. Scientists estimate that all the ants on earth weigh about as much as all the humans. If you consider how many ants it takes to weigh as much as one human, you can see how badly outnumbered we are. One educated guess -- by Harvard myrmecologist Edward O. Wilson -- puts the number of ants at 10 thousand trillion. That's 17.2 million ants per person.That's sort of an average number, however. Lately, we've been more outnumbered than usual."It's very possible and likely there has been something of an increase in ants," said Richard Little, staff entomologist for San Luis Obispo County [California]. "I would attribute it more or less to a natural cycle because of their food sources increasing."Most insects decline in number during the winter, so warm winters allow more to resurface in spring.The warmer winters provide more food for ants, who prey on some species of insects and scavenge the remains of others. Ants are the undertakers of the insect world. Nine out of ten insect carcasses are carried away by ants. The rains, meanwhile, have produced more grasses and weeds, which produce more food for the ants and for the insects they eat."The ant population this year has basically doubled or tripled," said Batchelor, who has gotten an average of six calls a day lately about ant infestations. With more ants living outside, more ants are venturing inside. Dry warm weather has given ants ideal conditions for activity, but it has also made them thirsty. "Now that the ground is so dry, there is no natural moisture for them, so moisture is one of the things they are looking for," Batchelor said.A construction boom may also be to blame. Soil disturbances send ants scurrying into neighboring properties. Local residents most often encounter the Argentine ant, also known as Linepithema humile. Argentine ants are small -- two to three millimeters in length-and brown, though they look black from a distance. They stream into homes in trails that resemble Interstate Five, searching for food and water, often entering along pipes or through cracks in the walls. Scientists believe Argentine ants first reached the United States on ships carrying coffee from Brazil to New Orleans in the 1890s. People first noticed them in California in 1905.Since then, they have pushed out most native species of ants in their path. "The Argentine ant is a very adaptable ant and competes very well with other ants for occupation of nesting sites," according to the Pest Control Field Guide. "It will out-compete and drive almost every other ant from an area, and is one of the few true enemies of the fire ant."The Argentine ant has become the most pesky ant species in Southern California, and has also infested the American South, California, Hawaii, South Africa, and Australia. They have been seen as far north as Vancouver.They do little damage to homes, however, and they don't sting. "They're more of an annoyance than anything else," Little said. "If you want to know a true pest, try having a fire ant infestation in your house. They constantly remind you if you take one misstep."Argentine ants can damage gardens and farms, however. In addition to foraging for food, Argentine ants tend aphids as livestock, acting like little two-millimeter cowgirls. They raise the young aphids, place them on plants, fend off their enemies, and feed on the sugary aphid poop, which is usually labeled with the lovely term, "honeydew."Frustrated people usually react to Argentine ants by grabbing a can of Raid. But that fits right into the ants' nefarious plans. Spraying Argentine ants will kill the visible adult workers, but the colony will replace them in a matter of weeks.Argentine colonies support thousands of workers and numerous queens. The colony will sometimes react to a disturbance -- such as an insecticide spraying -- by "budding." Budding occurs when one or more queens flee the colony with a team of workers to found a new colony nearby."Broadcast spraying around the perimeter of the house will only target the adult foraging ants," said Faith M. Oi, a University of Alabama entomologist who is battling that state's infestation of Argentines."Broadcast spraying is not recommended for some of these ants and can even make the problem worse by fragmenting the colony, which results in more colonies." The Argentine ant is winning the war. Humans cannot expect to eliminate them, according to scientists and pest-control experts. The best we can hope for is to keep them at bay."Eradication should not be the intent," said Brian Forschler, a University of Georgia professor. "You can only expect to reduce the numbers of foraging ants to the point that their appearance within the structure is rare."Nuke 'em HighIn the 1954 movie "Them!", the first atomic bomb test creates a race of giant ants in White Sands, New Mexico. The ants multiply and head for Los Angeles in a blood-thirsty quest for sugar.James Whitmore, James Arness, a scientist and his sexy scientist daughter go after the ants with bazookas, flame throwers, and cyanide gas. Those devices work nicely, as long as you descend into the giant tunnels and blow-up the queen, but that approach has proven impractical for home pest control. The movie has another flaw-its premise. In reality, ants have shown a startling immunity to radiation. The ants at White Sands were probably among the few species unaffected by nuclear tests. Scientists monitored ants in a French forest contaminated with hard cesium radiation. After 11 months the plants were dying, but ants showed no ill effects. They've shown a similar immunity to industrial pollution.So if humans do end up nuking and poisoning each other to extinction, guess who'll be in charge when we're gone?Chalk One UpThe most effective Argentine ant control known to man may be a mysterious substance called Miraculous Insecticide Chalk. The Chinese import is available from small corner markets, including several in SLO County that will remain nameless. It costs about 99 cents per box, and each box contains two sticks of chalk, enough to fend off ant infestations for more than a year."Draw several lines across the track which the insect used to take or around the insect's hidden lying place," the instructions read. "The insect will be killed instantly when it touches the powder of the chalk."Experiments performed in the New Times Product Testing Laboratory have shown this chalk will fend off Argentine ants for more than six months from the time of application. It's amazing, and it's illegal."Illegal products like this can be very dangerous," said Elin D. Miller, chief deputy of the California Department of Pesticide Regulation (DPR)."Because they are illegal, there are no controls over manufacturing. The manufacturer can change the formula from one batch to the next. You have no way of knowing if the ingredients are harmless, or a deadly poison."The chalk comes in a box that reads, "Harmless to human being and animal. Safe to use." But that hasn't proven true. A San Diego child was found unconscious in 1994 after eating a stick of the chalk.The child recovered in the hospital, and the EPA tested the chalk. It contained deltamethrin, a moderate toxin otherwise unavailable for home pest control. Deltamethrin has been approved for use in some commercial pesticides.The EPA would never approve a pesticide in a form that looks like another product, such as chalk, said Veda Federighi, communications director for DPR. That kind of packaging invites incidents like the one in San Diego.Federighi has first-hand knowledge of the chalk's effectiveness, however: "I was visiting my folks in the Bay Area last weekend," she said, "and they said, 'Have you seen this stuff? It works great!'"The miraculous and mysterious nature of the chalk has fueled rumors and launched misguided attempts to control ants with regular chalk. KSBY-TV even reported on the air last year that chalk doesn't repel ants. However, only Miraculous Insecticide Chalk has the power.Chemical WarfareArgentine ants put pest control companies to the test. To truly get rid of Argentine ants, exterminators must poison all the queens and all the larvae who live safely underground. This is a nearly impossible task, and the ants usually return."There are some days when I pull my hair out," Batchelor said, "because I get them controlled, and the next thing I know the homeowner's calling and saying 'Guess what? We've got them showing up at the other end of the house.'"Exterminators use a two or three-pronged approach. They spray a chemical around the perimeter of the property to deter the ants from entering, and they place a time-release bait in choice locations, hoping the workers will carry it home and feed it to the colony."We're trying more and more to utilize chemicals that are not an instant kill," Batchelor said.Baits have shown only limited success, however. Ants will avoid any food that has dead ants near it.The optional third prong is changing conditions around the house that favor ants. That means removing mulch and wood chips and clearing plants away from the outside walls. Argentines love to live under mulch and to travel on plant stems or hidden beneath blades of grass.They have also been known to move into homes, especially in winter. Argentines will form colonies in the sand beneath foundations, then travel up pipes and wires to get food and water from the home. They'll also form colonies in the insulation between walls.Batchelor believes ants have an important role -- including hunting termites -- so he tries to keep them out of houses."In some senses ants are good. They burrow down into the soil, causing soil aeration. They move things around. They assist in mulching. They clean up debris and dead insects," he said. "I'm in the pest control business, but I'm also an environmentalist."Know Your AntPeople have devised various "environmental" ant controls, also with little success.Diatomaceous earth is a super-fine powder -- actually the tiny shells of a microorganism -- that irritates ants and will deter them for a short time. Boric acid powder works in a similar way. Tanglefoot is a sticky substance often used as an ant barrier on plant stalks and tree trunks. It works until enough workers sacrifice their little bodies to form a bridge their sisters can use to pass over it.Environmental awareness may be helping the ants, but not so much by eliminating poisons. It has given them a reliable new food source -- recycling bins. People regularly supply ants with sticky sugary foods in the jars, bottles, and cans they set out for recycling.Which brings us to cleanliness. All the experts say this simple solution is the best solution to fending off Argentines and other ants."Find out why they're there and remove the reason why they're there, and they'll go away," said Richard Little. "It may take nothing more than cleaning up-keeping your kitchen clean, removing any food that is of easy access to them." When it comes to ants, according to the pesticide regulators, the best pesticide may be no pesticide."We still emphasize the low-tech ways of doing it," Federighi said. "Ants, like other pests, are looking for food and water. If you can deprive them of those things, they won't come in."Cleaning your house also eliminates pheromones, the chemical scents ants use to mark their trails. Wiping down a counter with soap and water will erase ant signals about the route to food.Smell that SmellArgentine ants do not speak Spanish. Argentine ants who have immigrated to the United States have made no effort to learn English. Instead, they communicate chemically using pheromones.Scientists have had fun with ant pheromones. The great Harvard myrmecologist, Edward O. Wilson, sprayed one worker ant with a mild acid that ants give off upon death.The worker continued attempting to forage and patrol and collect food for the colony as she had always done, but her sisters treated her as if she were dead. They ignored her attempts to help and occasionally tried to carry her off to the colony's graveyard heap. She could still walk and wiggle her antennae and lift 20 times her weight like other ants, but that made no difference to her sisters. At the University of Texas in Austin, scientists are studying ways of controlling ants by manipulating pheromones."In the last 30 years, the chemical languages of many species have been successfully exploited to control agricultural pests," said Edward L. Vargon of the Brackenridge Field Laboratory."Ongoing work by our research team on queen-produced pheromones indicates that these substances are instrumental in regulating colony growth and reproduction and that they may offer the most ecologically sound means of chemical control."Fly Away HomeOther brilliant ecologically-sound controls may also be on the horizon. Imagine, if you will, a fly small enough to pester an ant by zooming around its head when it's trying to work. They're called phorids, and they're so annoying they can hinder a whole colony's ability to forage.As if that's not enough, they have a horrid little habit that would keep Sigourney Weaver awake at night. A female phorid will land on an ant's back, penetrate its exoskeleton with a long sharp ovipositor, and inject an egg into the ant.When the egg hatches, the baby phorid will migrate to the ant's head, where it will slowly consume the contents as it grows. When the head is empty, the phorid larva exits through the ant's mouth.The ant, meanwhile, continues to function. Scientists have seen working ants strolling along with their sisters, despite cranial cavities empty except for a wiggling phorid larva. I'm sure you have coworkers like that, too. Dr. Brian Brown of the Los Angeles County Natural History Museum is leading research on the use of phorids to control invasive ants. Most efforts, so far, have focused on the Brazilian imported fire ant infesting the American Southeast. However, Brown has identified two species that prey on the Argentine ant. Stay tuned.Consider SurrenderIf these cutting edge defenses against the ants fail, humans might consider just giving up. It wouldn't be such a bad life. As long as we do our work 24 hours a day and contribute to the success of the colony, the ants will feed us and defend us from our enemies. It'll be similar to life in the Soviet Union. Or, we could end this senseless war now and try making peace with the ants on our terms. All they're doing, after all, is cleaning our houses, and a good housekeeper is hard to find.Jeff McMahon is an ant farmer in San Luis Obispo.SIDEBAR5:28 p.m. Friday: An employee of a local pest control firm (we'll call him "Bob") pulls an inspection truck into the company parking lot in an industrial area of San Luis Obispo. Emblazoned on the door of the truck are the words "Termite and Pest Control." He slips the vehicle into the space until the grille touches the leaves of a shrub at the edge of the lot. Bob steps out of the cab, closes the door, and heads into the office. In the cab sits a plastic cup Bob had purchased earlier at a local convenience store. It contains some ice and the remnants of a popular soft drink. It is sealed with a plastic top, which is penetrated by a plastic straw.5:47 p.m. Friday: Scout Myrtle 91649a is on routine patrol from her colony, cruising along the edge of a leaf. She's been on this leaf dozens of times before, but now something has changed. Clinging to the leaf edge with four legs, she reaches out with her front legs and antennae to caress a smooth warm surface. Carefully laying down a chemical pheromone trail so her sisters will know where she went, Myrtle steps onto the white surface to explore what appears to be a large new environment within her territory.8:12 p.m. Friday: Scout Myrtle 694230p (for reasons unknown to science, all worker ants are named "Myrtle") finds a slim opening between two black rubber surfaces on the side of the smooth object her sister had discovered two hours and 25 minutes earlier. She slips her body into the opening and discovers a vast interior environment. This environment seems constructed entirely of synthetic polymers useless to the colony. Nonetheless, Myrtle continues her exploration.1:14 a.m. Saturday: Scout Myrtle 27836w discovers a plastic straw inside the large chamber her sister discovered five hours and two minutes earlier. She scampers to the tip of the straw, then slips inside. She descends and soon encounters a sticky fluid. Her acute sense of smell detects the presence of high-fructose corn syrup. She scoops up a droplet of the substance with her mandibles, sucks it into her abdomen and rushes pack to the queen's chambers, following her own pheromone trail back to the colony. On her way, she urgently lays down a new chemical that tells her sisters, "This trail leads to FOOD!"4:07 p.m. Sunday: The manager of the local pest control company opens the door of the termite inspection vehicle. Inside he discovers a stream of ants, entering through the door, gliding across the dashboard to the cup holder. Hundreds of ants are flowing up and down the straw and circling the edge of the cup. He follows the trail to the front of the vehicle where it flows over a leaf and down a plant stalk to the earth. He grabs a bottle of Windex and douses the little bastards. Thousands of ants writhed in the ammonia for several seconds, then perished.