For the most part, ants do not cause any serious problems in yard and garden. Exceptions to this are the species that bite or protect aphids. Ant hills in flowerbeds and lawn areas can become a nuisance, however, as can ants that come indoors when foraging for food, returning to outdoor nests. If you have ant colonies that you wish to control, there are several things you can do.
A good least-toxic method is the use of boric acid baits. Boric acid baits can eliminate some ant colonies in about one week. The trick is to not kill the ants at the bait station, but to get the ants to carry the boric acid back to the nest, poisoning the members of the colony that never leave the nest. Most ants feed either on sugars or on protein, fats, or oils. To see which type you have, place small dabs of jelly and peanut butter (not mixed) where ants are seen and watch which food they are attracted to.
If they are attracted to the jelly, you can make a boric acid bait by mixing one-half cup jelly, such as apple jelly, with 1 1/4 tsp boric acid powder. Punch several holes in the lid of the jar, then screw the lid on tightly and seal with tape. The holes should be large enough for the ants to pass through to reach the bait. Place the bait jar on its side where the ants will come in contact with it. If the ants are unable to gain footing on the jar lid, you might want to scratch the surface with sandpaper or a pebble. If the ants are attracted to peanut butter, use that for your bait rather than jelly. If you find many dead ants around the bait station, which ever bait you use, lower the amount of boric acid in the mixture. If you are still finding live ants after a week to 10 days, increase the amount of boric acid. Although boric acid is of very low toxicity, it is best to place bait jars where children and pets cannot reach them.
Commercial boric acid bait stations such as DRAX Gel (for sugar-feeders) and DRAX-PF (for protein/fat/oil-feeders) are available from mail order companies such as Bozeman Biotech, and liquid baits from companies such as Gardens Alive! (Lawrenceburg, IN) and Harmony Farms (Graton, CA). Some stores carrying yard and garden supplies can also order these products. A disadvantage of commercial baits is you can not adjust the amount of boric acid if necessary.
Another method of ant control is to spread carbaryl granules labeled for ants in the infested area. To minimize damage to non-target organisms, place the granules where children, birds, pets, and wildlife cannot get them. Carbaryl baits are toxic to many beneficial insects as well. Commercial ant insecticides such as chlorpyrifos and diazinon can also be used. Remember that these insecticides are of higher toxicity and will kill other organisms, including beneficial insects, while remaining in the environment for longer periods of time. When using any insecticide, natural or synthetic, read and follow all label instructions.
Repeated floodings with a garden hose is said to encourage certain species of ants to pick up and move the colony. This method works for some ant species but not others. Some species do not like damp conditions and will eventually move to avoid them. If you choose to try this method, let the garden hose trickle down into the ant hill for about ½ hour every few days. It takes patience and time (if it works at all), but is virtually non-toxic management for the ant species for which it is effective.
For quick but temporary results, you can drench ant colonies with solutions of insecticidal soap, which are simply highly refined soap and are considered nearly non-toxic. Drenching ant colonies with insecticidal soap will not eliminate ants deep in the nest.
References:
Cranshaw, W., M. Brewer, S. Armbrust, and S. Lajeunesse. 1994. Household Insects of theRocky Mountain Region. Extension Publication 557A, Montana State University, Bozeman, Montana. 90 pp.
Olkowski, W., S. Daar, and H. Olkowski. 1991. Common-Sense Pest Control; Least-toxic Solutions for Your Home, Garden, Pets and Community. Taunton Press, Newtown, Connecticut. 715 pp.
Ortho Problem Solver. 1989. Ortho Information Publishers, San Francisco, California. 1,040 pp.
Written by Sherry Lajeunesse, Extension Urban Pest Management Specialist. Sept., 1997
Categories: Ants, Bait
Date: 11/26/01