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December 18, 2010 Boric for Ant Problems Originally published in the Contra Costa Times by UC Master Gardeners All pesticides are toxic. Careful use of low

toxicity baits can be effective in the home. SUMMARY Q: With the recent rains and cold food such as spills, crumbs, garbage, weather my house has been invaded by dirty dishes, and pet food. If these other To control ants indoors, ants. I heard that you can use boric acid food sources are present, it may be first try exclusion by to kill ants in the house, and that it’s non- difficult to get ants to take ant baits. caulking and otherwise toxic. How do I use it? closing up openings The ant most commonly associated with where they enter. A: All pesticides are toxic; that’s how household invasions in California is the Cleaning up food sources they work. Boric acid, however, has low , although other species will also help. If baits toxicity to humans, pets, and non-target invade homes too. To identify the are necessary, boric acid species when used properly, and it is species of ant you can go to: is an effective yet low- effective on a wide range of pests http://ipm.ucanr.edu/PMG/PESTNOTES/pn toxicity control. in the home, including ants and 7411.html . . The key words here are “when used properly”. Read the Knowing a little about ant behavior and directions on the package and follow ecology will help you manage the ant them exactly. Never leave any pesticide, population. The tendency of the including boric acid, where children, Argentine ant to form columns as they pets, or wildlife can get into it. invade is actually helpful. It will make it easier to use ant baits. Try Exclusion & Clean-Up First: It is common for ants to invade living Boric Acid Is Less Toxic: spaces as winter approaches. Ants There are several active ingredients in provide valuable services in the ant baits, but boric acid is a good choice environment, however, if their nests are because it is effective and relatively non- flooded or their food sources disappear, toxic. Read the product label to see they invade homes in search of warm, what the active ingredient is. Those dry nesting places and food. Any containing boric acid will generally management program should include include the word boric or on the closing up cracks and other openings to label. Boric acid is toxic to plants so exclude ants, and cleaning up sources of should not be used around them.

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ccmg.ucanr.edu December 18, 2010: Boric Acid for Ant Problems, page 2

Several types of boric acid pesticides are Prefilled bait stations might be the available, including dusts, liquids, pre- easiest kind of boric acid pesticide to filled bait stations, and gels. Each use, and there are several brands formulation has its own uses. available. Following the manufacturer’s directions, place one or more bait Pesticide dust can be useful in stations on or near the column. If ants “A thin layer of boric basements, under houses, in wall voids, don’t appear to be eating the bait after and other places where it won’t be several hours it is possible they aren’t acid dust, widely unsightly. It should only be applied interested in the attractant (usually where it will not get wet, because once sugar- or protein-based) at the moment, spread, will be more wet, it is largely ineffective. A thin layer so try another brand. It’s useful to keep of the dust, widely spread, will be more two or more brands of ant baits on hand, effective than clumps effective than clumps of dust. The ants sealed in an airtight container, if you walk through the dust and get it on their have frequent invasions. of dust. The ants walk bodies, and then ingest the dust when they clean themselves. Whether dust, gel, or liquid, worker ants through the dust and that are out gathering food for the Boric Acid Gels & Liquid: colony will pass along some of the get it on their bodies, Boric acid gels can be applied in cracks poison they ingest to other ants when and crevices, or can be applied to bait they share the food they’ve collected. and then ingest the stations or even small pieces of Boric acid is a slow-acting poison, so it cardboard or jar lids. Gels should be doesn’t kill before it can be spread to the dust when they clean used close to the invading column where larger population, and this is what the ants will discover it readily. Exposed makes it so effective. themselves.” to air, gel will remain effective for about three days, so it needs to be replenished Once the invasion is over (you’ll see frequently. fewer and fewer ants until they’re all gone after several days), pick up all baits Liquid bait, usually sugar with and either take them to a household boric acid, can be applied to bait stations hazardous waste facility or seal them in or small containers, and should be an airtight container for use the next placed right in the column of ants so time they’re needed. they can’t miss it. The liquid may need to be replenished every few hours or For More Information: days, depending on how fast the ants eat Learn more about using boric acid on it. It remains effective as long as it is household insect pests at: liquid. http://ipm.ucanr.edu/PMG/PESTNOTES/pn 7411.html .

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