What Pests Want in Your Home

How you can thwart some common household pests without poisoning yourself

  • Peter Jaret
  • Aug 01, 1999
Reaching for the bug spray is the last thing on Sheila Daar´s mind, even as a trio of Argentine ants climbs a potted orchid in her Berkeley, California, living room. "These guys probably hitched a ride when we brought the plants in for the winter," she says almost affectionately as the visitors disappear into a tangle of roots.

A second ant contingent makes its way along another pot, and still the biologist seems undisturbed. She marvels, "Argentine ants have developed a cooperative system with multiple queens, hundreds of them sometimes. They´re quite remarkable. But of course ants of any kind can be endlessly fascinating." Perhaps for a scientist. Most of us, however, don´t find the sight of ants indoors so enthralling. We want them out. Now. And the first thing many Americans do is reach for the poison.

Don´t, says Daar, an expert in least-toxic pest control. Sure, spray might knock out some worker ants. "But you´d never get to the queens, which are back in the nest popping out eggs," she says. And you´d be spreading toxic chemicals in your home. Instead, to control these particular interlopers, she has put each pot high and dry on an inverted saucer that sits in a larger saucer holding soapy water. The soap breaks the surface tension, and ants won´t try crossing it; if they do, they sink.

Daar´s moats are part of an approach called integrated pest management, or IPM. If moats aren´t enough to cope with an ant problem, for example, baits might do the job. The idea is to give the ants food, accessible only to them, dosed with a low concentration of a toxic chemical they will carry back to the nest. Such strategies are alternatives to the slash-and-burn approach that has unleashed a witches´ brew of pesticides into the environment. The most toxic of them available off the shelf for use in the home are carbamates and organophosphates, which work by damaging nervous systems and come with stern warning labels--for good reason. Not only do such poisons pose a danger to pets and wildlife, they may contribute to human health problems, especially in children.

It is difficult to measure such risks in humans, especially the long-term effects of low doses. But studies using information from large-scale accidents, damage to wildlife, industrial exposures and laboratory studies link many pesticides to health effects ranging from immunological problems to birth defects to brain damage.

There also are practical reasons to avoid the most toxic pest-control methods. For one thing, they often cost more. For another, many pesticides no longer work well. "As many as 500 species of the most common insect pests are now resistant to one or more widely used insecticides," says Daar, former executive director of the Bio-Integral Resource Center in Berkeley, California, and now head of the Daar/IPM Consulting Group, also in Berkeley.

In recent years, a growing number of businesses and government agencies have turned to integrated pest management. Three years ago, the city and county of San Francisco--with the help of the Bio-Integral Resource Center--took the extraordinary step of replacing the use of many of the most dangerous pesticides with other strategies. The effort includes parks, public transit, utilities and city buildings. By the year 2000, all pesticides will be banned for city use except certain choices deemed to be least toxic. San Francisco is not alone: Two counties in New York have passed similar restrictions, and several states recommend or require the use of such techniques in public schools.

No such requirements govern private use. But least-toxic strategies do exist for every type of pest you might find. And once you study up on certain creatures, you might tolerate them more. The occasional ant scout, for example, doesn´t faze Daar. "Ants are the primary predators of termites," she explains. "The best approach is to eliminate them where they´re a nuisance and let them live where they can do some good." Even if you hire someone to take care of a pest problem, increasingly you can find professionals who practice integrated pest management. Some of their innovative treatments might involve using heat or electric currents to beat seemingly intransigent infestations.

There is plenty, however, you can do on your own. On the following pages, we offer a few examples of common household pests, their habits and ways you can thwart them in your home using easily available, least-toxic methods.

Few sights are more repugnant than cockroaches skittering into the shadows. Roaches have never been shown to transmit human disease, but their excrement and saliva--both of which can end up in your food as well as in the air--can trigger severe allergies. Americans spend $1.5 billion a year spraying for cockroaches, often to no avail, since the bugs have grown resistant to many common insecticides.

Still, cockroach behavior offers clues for combating the pests. There is a wonderful word for their desire to feel the walls of cracks and crevices tight against their backs and bellies: thigmotactic. But for homeowners there is little else about the creatures to appreciate, including a new finding about their trails. In a recent study of German cockroaches, the most pervasive members of the species in North America, University of Florida-Gainesville researchers found that the creatures defecate as they travel, leaving trails of waste. Other roaches then follow the trails. In some cases you even can see the brown lines. Believe it or not, this news is not all bad, as it means scientists may be able to create new baits. For now, it means that you can use the telltale lines to decide where to place bait.

You also can use nontoxic sticky traps, available at hardware stores, to find out where roaches hang out in your home. Or you can fashion your own trap by spreading petroleum jelly on the inside of the mouth of a glass jar and putting bread inside as bait. Place the jar upright in a corner or near sources of water, warmth and food--such as refrigerators or kitchen sinks. The bugs fall into the jar and can´t get out.

One way to make roaches unwelcome is to remove sources of food, including waste and pet food, although truly starving them is next to impossible: Roaches eat everything from grease spots, to mold, to each other, and they can fast for many weeks. They can´t, however, last long without water. In experiments, entomologist Richard Brenner of the U.S. Department of Agriculture´s Agricultural Research Service discovered the creatures avoid drying air currents. "Deny them water and you´ve hit them hard," he says. Although they always can help themselves to water from a toilet, you can cut way back on their other sources by fixing dripping faucets and other leaks and keeping dry areas where water may collect, such as in the bathtub or sink.

If an infestation persists, you can turn to baits that contain poison or to plain boric acid, one of the few toxics to which roaches haven´t developed resistance and also one of the least-toxic pest-control chemicals. Boric acid is available in bottles with straw-type nozzles that help deliver it to crevices. If you use baits, place them in corners and under sinks, refrigerators and stoves.

And keep an eye out for new treatments. In a recent experiment in a Baltimore home, Brenner used hot, dry air currents to drive roaches out of hiding places. Then he vacuumed up the fleeing creatures, using a high-efficiency particulate air (HEPA) vacuum so he didn´t spread allergens. He followed up with gel bait in cracks and crevices. Nine months later, the infestation had not recurred.

There are no two ways about it: You do not want mice in your home. They can damage food, clothing and electrical wires, and they spread disease such as meningitis, salmonellosis and, in the Southwest, hanta virus. The U.S. Environmental Protection Agency estimates that in six months one pair of mice can eat as many as four pounds of food, contaminate another 40 pounds of food and deposit 18,000 droppings.

The most common mouse in the home is the house mouse, which moves in to stay. It breeds year-round, nesting behind walls, under floors and above ceilings. It usually ventures no more than 30 feet away from its nest. A single pair may have 50 young in one year. Agile and fast, mice can squeeze through a hole the size of a dime. They inhabit undisturbed places, shred available materials for nest building and chew through almost anything in their way.

The best way to get rid of mice that have already moved in is to trap them, and the biggest mistake you can make is to skimp on the number of traps. For bait, try using cotton balls on at least some traps. They will target females, which try to appropriate the cotton for nest building. On other traps just about any food will do. One favorite bait is peanut butter mixed with rolled oats or raisins. Don´t waste your money on devices that emit ultrasonic sounds to ward off mice; there´s no evidence that they work.

Mice travel along edges, so try placing traps with the bait end facing the wall. Put them in places you think mice have already traveled; chances are good they´ll pass that way again. They´re also curious about changes in their habitat, including traps. Daar advises putting the traps out baited but unset for a day or two so the mice don´t perceive them as threats.

Also, fill holes that allow rodents access into the house, using materials such as steel wool, caulk or plaster. And of course, store food, particularly grains, in tight-fitting metal or glass containers. Don´t count on plastic; mice can chew right through it. Keep pet food and garbage sealed in mouse-proof bins. For stubborn infestations, you may want to consult a professional. If you consider using bait that contains poison, keep in mind that rodents worldwide are developing resistance to rodenticides, and as a result the toxics are ending up in mouse-eating predators such as foxes and birds of prey.

If you see large black ants in your home, or if you find piles of fine shavings in out-of-the-way places, you may have a problem bigger than a mere nuisance: carpenter ants. The sawdust can mean the creatures are tunneling through moist wood in the structure of your house, using their jaws to shave off bits that can add up to big damage. At the least, getting rid of carpenter ants means finding the nest, solving moisture problems and replacing infested wood. All of that can mean calling in a professional. So do more sophisticated techniques such as heat treatment or the use of a device called an Electrogun that sends an electric current into the ants´ tunnels (it is also used on termites).

Often, however, coping with ants in your house takes nothing more than soapy water, good housekeeping and caulk. As alarming as the sight of ants swarming over the dishes you left in the sink might be, the ants are not there to hurt you. And stinging ants rarely enter the home. (If you live in a region of the South inhabited by fire ants, however, learn to recognize them just in case they do show up.)

The visitors in your house are all female worker ants, and their job is to carry nourishment back to the colony and its presiding queen. Look beyond the teeming mass in your sink, or wherever else they have found food, and you´ll likely find a line of ants marching to and from the scene. "Many ant species follow chemical trails excreted by their scouts, so it can be easy to trace the line back to where they´ve entered," says Daar.

Once you´ve found their point of entry, block it with a temporary patch of petroleum jelly, tape or even a dab of toothpaste. Later you can close the opening permanently with silicone caulk. Then squirt soapy water on the ants or use a sponge dipped in soapy water to wipe up the trail of ants and its telltale chemical highway, rinsing the ants off as you work. And clean up the food that attracted them in the first place. That way, any new ants that appear won´t find trails left by their cohorts, and they won´t find any food that prompts them to lure new cohorts to the scene.

Since ants prey on termites, flea larvae, bedbugs and other pests more troublesome than ants, biologists advise not panicking at the sight of a scout or two. You even might think of them as little crumb cleaners. But if you have a colony within your house, or if an invasion gets out of control, you may need stronger measures.

The least-toxic ant poison is boric acid, which ants carry from baits back to the nest. As they share the food, the whole colony ends up eating enough boric acid to kill most members. You´ll find boric-acid ant traps at hardware stores. Some have concentrations of boric acid as high as 5 percent, and those usually work quickly, but baits with lower concentrations of the toxic are ultimately more effective. That´s because if contaminated workers die before they make it back to the nest, a queen will keep laying eggs. If you can find baits with 1 percent or even .5 percent of boric acid, you´ll have more permanent results.

If ants die left and right around baits of any strength, try leaving the corpses where they are for a day. Other ants likely will take them to the nest, where they too will poison the colony. And be patient: Baits should start killing ants in a day or two, but poisoning the nest can take longer.

The names may be charming--Indianmeal moths, drugstore moths, sawtoothed grain beetles, confused flour beetles--but the damage these invaders do is anything but. Not only do pantry pests consume your food and contaminate it with their waste, some mites that can flourish in products ranging from grains to tobacco cause rashes and even flulike symptoms in people. Whatever you do, however, do not reach for the bug spray. It´s best to avoid using insecticides wherever food is eaten, prepared or stored.

For a creature that considers a pantry to be a gold mine, food such as boxes of dried noodles, bags of flour or boxes of cereal are ideal places either to lay eggs or to consume the mother lodes of food--or both. More than 200 species of beetles, moths, mites and silverfish can live in the food in your cupboard. And far more species of other, unseen life exist in your food in the form of fungi and bacteria that can attract the more visible pests.

One of the most common pantry bugs, to give one example, is the Indianmeal moth, which feeds on all sorts of food--including crackers, bird seed, dried fruit and candy. You might recognize the pest from the adult´s appearance, distinguished by bicolored wings of gray and reddish brown. Or perhaps you´ve encountered evidence of the larvae, which spin silk as they move around, webbing together bits of food and leaving behind collections of waste. Indianmeal moths live as long as 10 months. A single female lays as many as 400 eggs.

Even if you are scrupulously clean, you can be surprised by an infestation of pantry pests. That´s because the main way the insects enter your house is through the food you buy. And that´s why it´s a good idea to store all food in tightly sealed containers that will stop marauders from spreading through the riches in your kitchen.

As soon as you find pests in the kitchen, track down their source. Look first in stored foods such as flour or grains that are open or have relatively flimsy packaging. Once you´ve found the infested food, you might want to seal it in a plastic bag and freeze it for several days to kill the invaders before throwing it away. Be sure to check thoroughly for signs of insects in other food stored nearby and eliminate them too.

Afterwards, a few simple housekeeping strategies will lower the odds of new infestations. Regularly clean all areas where food is stored, including pantry shelves and bins. Make sure to include dog food, a frequent source of pantry pests in the first place. Finally, since moisture encourages infestations of fungi, bacteria and pests, keep food storage areas dry.

Arachnophobes, listen up: Despite their creepy-crawly reputation, most household spiders are perfectly harmless to you. Very few bite people, and fewer still cause health problems. Of the 3,000 kinds of spiders in the United States, only four--the black widow, the brown recluse, the hobo and the yellow sac--are known to pose serious threats to humans. But even they would rather not tangle with you. And other spiders can help control these species, either by preying on them or competing with them for food and web sites.

All spiders really want to do, aside from reproduce, is spin their webs to catch prey. Then they sink fangs into the doomed creatures, inject paralyzing toxins and tear them open to extract the liquids within. As gruesome as that may sound, it´s worth remembering that spiders´ prey often are pests that do cause harm to people. Many so-called spider bites are from bugs such as fleas, mosquitoes, bedbugs or biting flies--some of the very pests spiders eliminate. "So if you don´t mind leaving a few webs up in inconspicuous places, you´ll have resident pest-control professionals in your house all year long," says Daar.

If you can´t bear the thought of sharing your home with even the most harmless spiders, however, try limiting their food supply: Put up screens to cut down on the number of flying insects inside the house, and turn off lighting that attracts bugs. If that´s not enough, use a HEPA vacuum (so you don´t spread allergens) to remove spiders and their webs. To limit populations, you can try targeting female spiders, which usually are much larger than males. As for pesticides, remember they often are not effective on spiders indoors unless the spray touches the creatures.

Just in case you do encounter the spiders that can hurt you seriously, it´s a good idea to know what they look like and where you might find them. Female widows have a distinctive round shape marked with a red hourglass on the underside; you don´t have to worry about the males. The recluse is a muddy color with a small, dark marking in the shape of a violin high on its back. The hobo, found only in the Northwest, where it probably hitchhiked into the Port of Seattle from Europe early in this century, unfortunately is a rather nondescript brown. The yellow sac has fairly colorless legs and a yellowish body.

These spiders can show up indoors in undisturbed places such as closets, attics and cellars. Bites are unlikely to kill you, but they can make you very sick. If you are bitten, seek medical attention immediately and take the culprit with you to the doctor if possible.

Free-lance writer Peter Jaret has a new appreciation for the ants roaming his home in Petaluma, California. Among the many excellent resources for more information are the book Common-Sense Pest Control by William Olkowski, Sheila Daar and Helga Olkowski (The Taunton Press, 1991) and the Bio-Integral Resource Center web site at www.birc.org/.

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