Nuisance Ant Control For Homeowners
by Jack DeAngelis, PhD of LivingWithBugs.com
Ants that you see around the house fall into two broad categories, carpenter ants and nuisance ants. Carpenter ants (see http://www.LivingWithBugs.com/carp_ant.html) are large, powerful ants that nest above ground in cavities and may cause damage when nests are in homes. Nuisance ants, on the other hand, don't do structural damage but can be become a real nuisance just by sheer numbers. Ants enter homes from nests in walls or in the soil around or under the house. They come in search of food and water. During dry, hot weather water may be the most important lure. Since nuisance ants don't normally cause damage their control is less urgent.
Control of nuisance ants... Use baits, NOT sprays!
Unfortunately, many of us grab a can of bug spray at the first sign of ants and just spray away. STOP DOING THIS. Aerosol sprays have their uses but nuisance ant control is not one of them. Sprays are very difficult to use correctly and may end up being messy and ineffective. The best and safest way to control nuisance ants is with baits.
While baiting is not the easiest or quickest method, it works and is relatively inexpensive. Ants need protein, fats and sugar (carbohydrate) to sustain colony growth. The idea is to attract ants to a bait that they carry back to their colony feeding it to their "nestmates" and the queen. Baits must be attractive to foraging workers and must kill slowly... not be so acutely toxic that workers don't have time to carry it back to the nest and feed it to colony members.
Most of the time baits that contain sugar work best but sometimes fats and protein will be needed for maximum attractiveness. Poison baits consist of two main parts - the bait part (sugar, protein, fat) and the poison or toxicant. One of most effective and safest toxicants is sodium borate or boric acid. Borates exhibit relatively low human toxicity while being highly toxic to insects. Check labels and look for borate or boric acid as the active ingredient.
The trick with baiting is to be certain that the bait you use is acceptable to the ants you are trying to control. This sounds obvious but too often bait stations are put out and never checked for activity. If the ants are ignoring the bait, replace it with another. If the first is sugar-based try one that is fat-based. If your ants are ignoring your homemade bait stations (see below) try one of the pre-packaged bait stations. You can also mix a little vegetable oil with the sugar-based borate baits. The point is to FIND A BAIT YOUR ANTS ACCEPT.
(Note from NH: In my experience, you may not even see any ants taking the bait! Don't be discouraged... some ants in the nest are more picky than others. Be persistent with your bait application if you want to achieve success!)
Finally, poison baiting may take awhile to work. Give it a couple of weeks. Continue baiting until you see no more ant activity at your stations. Replace baits if they dry out.
Insects enter houses in search of food and water. If you limit access to both you'll go a long way toward eliminating all your pest problems. Clean up spilled food, fix leaking pipes and other sources of water. Spilled, dry pet food is a commonly attracts many insect pests including stored product pests like Indian meal moth.
Locating the bait...
Even one ant finding a suitable food can call in many nestmates. Entomologists use the phrase “recruitment to the bait” to describe how once an acceptable food source is located worker ants communicate the location to nestmates. More and more ants find the bait over time.
An acceptable bait placed in the path of ants will be surrounded in a matter of minutes. This is important because it means that the process is not haphazard. Once an acceptable bait is found by a single worker other ants will be recruited to that bait source.
Homemade bait stations - shielded or not shielded?
The easiest and cheapest bait stations are simply small pieces of waxed paper with a few drops of boric acid-based liquid bait like Revenge, Terro, etc. Place near ant trails, one station per trail. While this bait is relatively low toxicity you don't want kids or pets getting into it. If there's a chance that either will contact the bait you'll need to devise some sort of shield that allows ants in but keeps small hands and paws out. One effective shield is an upside down plastic container with holes cut to let in ants. A weight on top will hold it in place. The downside of a cover is it makes checking the bait for ant activity more difficult.
What role do exterminators (pest control operators or PCO) play?
If you search you'll find one that uses baits. Most of the time nuisance ants can be controlled by homeowners without the expense of a PCO but carpenter ant infestations require these services. If you insist on hiring an exterminator for nuisance ant control (you hire someone to cut your grass, too, don't you?) find one that uses baits. Very large nuisance ant nests may need wall void treatment with insecticide and this is definitely an operation best left to a professional.
Suppress vs. eliminate...
Be realistic. It is unlikely that you will be able to eliminate the entire colony with baiting. Large colonies are especially difficult. There may be numerous colonies around the home in the soil and in the walls. Most of the time these ants forage outside and you'll never be aware of them. Your goal should be to suppress colony development with baits applied several times a year when you notice activity. Keep it simple, cheap and safe. Good luck.
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