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Controlling Ants in the Home and Landscape

pharoh ant

Pharaoh Ant

Spring is the time of year when ants are swarming to mate and form new colonies. Many ant species are found in Florida, but not all are household pests and some only cause problems occasionally. The University of Florida/IFAS highlights 11 species of household pest ants, including black carpenter ants, crazy ants, Pharaoh ants, imported fire ants, Argentine ants and big-headed ants.

Most ants eat a wide variety of foods, including honeydew, sugars, proteins, oils, seeds, plants and insects. Ants don’t eat fabrics, leather or wood in houses, although they can clean out decaying or termite-damaged wood for their nests.

There are several strategies that can be used to control ants: habitat modification, sanitation, physical and chemical controls.

Habitat modification includes reducing ant entryways and their access to food. Many of these alterations will be permanent and make a long-term impact on the number of ant invasions. Clear landscape debris away from the house so the ants don’t have places to make a nest. Use a silicone caulking compound on all potential entryways, starting with the site where the current trail of ants is getting into the house. It is important to seal as many cracks as possible, especially around baseboards, cupboards, pipes, sinks, toilets and outlets. Silicone caulks are flexible, easy to apply and long-lasting. Use weather stripping around doors and windows where ants may enter.

Sanitation is critical to prevention and control. Don’t make it easy for them. Clean up food debris and spills, especially those involving sweets, as quickly as possible. Occasionally give all food preparation areas a complete cleaning, focusing on areas where grease and food debris may build up. If dishes can’t be washed right away, rinse them to remove all food debris. Keep foods sealed in air-tight containers if possible. Ants can get through cardboard. Screw top jars must have a rubber seal; otherwise the ants can follow the spiral ridges to get into the jar. Drain the sink and remove any food debris. Put garbage in sealed plastic bags and place it in the outside garbage bin. Rinse bottles, cans, wrappings and other items that have food residues clinging to them before putting them in the recycle bin. This also helps with fly, roach and rodent control.

The first thing you can try if ants invade the house is a mixture of soap and water in a spray bottle. This will quickly kill the ants and they can be wiped up with a sponge and washed down the drain.

If these methods don’t work, you may have to resort to chemical control. Remember that whenever you use a pesticide you must follow the label directions exactly because it’s the law and also to avoid harming people, pets, wildlife or the environment.

Boric acid is a valuable chemical control tool that comes in several formulations including dust, gel bait and aerosol. It acts as a stomach poison, but is fairly non-toxic to mammals. If kept dry it can remain active for long periods of time. It can be used for crack and crevice treatment, dusted into wall voids and spaces behind and under cabinets, or over large open areas. Be sure to wear a dust mask to avoid breathing the material.

Diatomaceous earth and silica aerogel are other products that kill ants while not being directly poisonous to humans. Both kill insects by drying them out. They work well as crack and crevice treatments and in wall voids.

Baits are an important chemical control method because they greatly reduce the amount of pesticide that must be used to kill ants.   Foraging ants take the bait back to the nest to feed to other members of the colony resulting in colony death. Once the queen is killed there is no more ant production, because the queen lays all the eggs. Even if the queen is not killed, baits will usually stop an ant invasion. If a colony has been starved by good cleaning practices, baits will be more readily accepted. There can be some problems with baits because you have to know if the ants are seeking a sugar, or protein, or fat bait. A colony that eats protein bait one week may be more interested in sugar bait the next.

It is important to place the bait stations along ant trails without disturbing the trails or killing any of the ants. The workers will find the bait, carry it back to the nest and feed the queen, eliminating her and future populations. Only use baits when you have an ant problem. If you put them out when there are no ants you may attract ants into the house. Don’t spray pesticides when using baits. Spraying the bait stations will repel ants and scatter them, making it harder to control them.

When treating for ants outside, the best management method is to broadcast granular baits around the landscape and in lawns. These baits can usually be used for individual mound or nest treatments too, but be sure to check the label.

To have the best success when baiting, make sure you use fresh bait, wash your hands before baiting to prevent contamination from other products, and don’t smoke because nicotine will contaminate the bait. A good rule of thumb for outside baiting is to apply on a day you would have a picnic and not immediately before or after a drenching rain. Turn off your irrigation, too.

It should be noted that native ants are valuable in many ways. They prey on many pest insects including fly larvae and termites. Ants aerate soil and recycle dead animal and vegetable material to help form top soil. They are also very important pollinators and provide a great service to the environment. The goal is not to eliminate ants, but to manage them and prevent them from getting into your house.

For more information or for help identifying ants or termites, visit your local University of Florida Extension at 12520 Ulmerton Road, Largo. The Lawn and Garden Help Desk is open from 8 a.m. to 5 p.m. Monday through Friday.  To speak with a horticulturist, call 727-582-2110 on Monday, Tuesday or Thursday from 9 a.m. to noon or 1 to 4 p.m. You can also visit our website at www.pinellascountyextension.org. Some ant-specific websites are: IMP for Ants in Schools (http://schoolipm.ifas.ufl.edu/newtp6.htm); Ants (http://edis.ifas.ufl.edu/ig080); or Pest Ants (http://edis.ifas.ufl.edu/in018).

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