Can you control ants?

Yes, with persistence, multiple plans of attack, and knowledge of their social habits Armies of marching ants invade your kitchen, bathroom, plants--these pests travel wherever they can find even the smallest morsel of food. Get rid of them, and they always seem to come back. Can ants be beaten? We asked that question of entomologists and pest controllers throughout the West. Their answer: maybe not beaten, but at least beaten back. It takes persistence and multiple plans of attack to control them.

First, get to know the enemy Ants are social creatures. They usually live in highly organized colonies underground, under rocks, in tree cavities, in pavement cracks, or in buildings. Each colony consists of one or more egg-laying females (queens), a few males, and anywhere from a few hundred to several thousand sterile workers. Queens and males have wings, which they use just once, in a mating flight. It's the wingless workers that you usually see. Their job is to scour the countryside for food--usually sweets, meat, or grease--and bring it back to the colony to feed the queen and developing larvae. Many different species of ants live in the West. Some are more likely to become pests than others. The Argentine ant is the commonest household pest. Small and brownish in color, it travels in definite trails and nests outdoors in pavement cracks or moist soil under shrubs, although it can nest in walls or crevices in houses. Argentine ants are most active in summer but can often become a problem in winter after cold or rainy periods. With one or two exceptions, it's not that important to know which type of ant you have. Control measures are the same. Exceptions are a few species of carpenter ant that can bore into wood and weaken a house's structural supports. One of the West's largest ants, often reaching 1/2 inch long, they can be found in northernmost California and high-elevation areas. An exterminator may be necessary to control severe infestations. The pharaoh ant--tiny and light yellow--has proved especially difficult to control with chemicals. Nests are often concealed inside house walls or other difficult-to-find locations. Next month, a new bait that effectively controls pharaoh ants is due to be released for use by professional exterminators. Most state cooperative extension services offer bulletins that will help you identify the type of ant you have, but one stands out among the others. For a copy of the color bulletin 21433, A Key to Identifying The Ants of California, sent $2 to ANR Publications, 6701 San Pablo Ave., Oakland 94608.

Start by cleaning up, sealing entryways, and trying to find the nest The first step in getting rid of ants is eliminating their food source. Keep bathrooms and kitchens as clean as possible and store all food in tightly sealed containers. Sometimes you can keep ants out of the house by tracing the workers' trails backward and sealing their entry points with caulk. But more often than not, they'll come in another way. If you can trace ants all the way back to their nest, you can deal with them more directly. Walk the perimeter of your house and look for a trail of ants entering along the foundation. Follow the trail back until you find the colony, marked by disturbed soil, and cracks or a hole with a lot of ants moving in and out. Treat the trail, nest, and area around it with a chemical labeled for outdoor ant control, such as diazinon, dursban, baygon, or bendiocarb. Follow label directions exactly. Some homeowners have reported success eliminating ant colonies with soap sprays or mixtures of finely chopped citrus peels and water. Citrus oils are reported to be useful controls, but there have been no scientific studies to prove it. If you can't find ants entering your house, they may be nesting indoors; baits may be your best bet, as described below.

Use chemical barriers to keep ants out Spraying, dusting, or soaking the outside perimeter of your home with one of the chemicals labeled for outdoor ant control may keep them out for four to six weeks. Dursban, baygon, and bendiocarb are labeled for indoor use. They can be effectively used to create barriers under the house, behind cabinets, or wherever ants may be moving. Pyrethrin sprays are also labeled for indoor use but are most effective in killing ants on contact; they have a short residual life as a barrier. Use these products with extreme care, and follow label instructions exactly. Make sure everything is cleaned up and put away before you spray indoors. Two less toxic materials can be used as ant barriers: boric acid, a slow-acting but long-lasting poison; and silica gel, which kills ants by dehydration. To be effective, these products must be kept dry.

Baits--sometimes they work, sometimes they don't Poisoned baits are an attractive alternative to other ant controls because you don't have to spray or dust large areas or know exactly where the nest is. To be effective, workers must eat the bait, then live long enough to carry it back to the colony and feed it to the queen and others. Whether they do this or not depends on several factors. First, they must be attracted to the bait. If there is other food around, or if they need another type of food, they probably won't be. Second, the bait must be lethal but slow acting; if the bait kills too many ants too soon, they'll get the message and stay away. Place baits where ants will find them, such as at entry points or along trails. If they aren't attracted to one type, try another. Even if all goes well, baits may take as long as six weeks to eliminate a colony. Ant baits contain several different poisons, usually combined with something sweet or greasy. The poisons range from very toxic to humans, such as arsenic, to less toxic materials, such as boric acid. The baits also come in various types of containers, some of which leave poisons where children or pets may be able to get at them. Don't forget these considerations when choosing baits and deciding where to place them. Several new ant baits containing the poison hydramethylnon and a secret new ant attractant have shown promise in tests at the University of California at Riverside. They are currently being registered by the EPA and may be available to homeowners as early as next year.