Best way to control fire ants may not be to kill them but bait them

Published 12:00 am Sunday, September 17, 2006

Imported fire ants, introduced from South America to the Gulf Coast area by accident in the early 1900s, have marched across the southern US and are now establishing themselves in Western states including California. These tiny insects have created big problems for people, pets and agricultural business, making their eradication a top priority of the United States Department of Agriculture as well as state agencies.

Ant colonies may move from one location to another due to flooding of their nest because of heavy rainfall or another disturbance, or even during mating. They also travel by the most modern means &8212; hitching rides in cars, boats or trains. Ants can quickly affix themselves to soil, plant roots, sod, hay bales or wood, making them even more mobile when these products are moved.

According to the USDA, &8220;A new colony begins with a &8220;nuptial flight&8221; of winged males and winged females, usually on a warm, spring day. After mating occurs, males drop to the earth and die. Females also drop to the ground, and those that successfully elude predators and survive drought and rain seek out nesting sites and burrow underground. A new queen sheds her wings and lays 12 to 24 worker eggs, which she tends constantly. Upon hatching, the workers, all of which are sterile females, take over all colony functions except reproduction, while the queen lays eggs. She may produce more than 200 eggs per day.&8221;

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The USDA researchers have also found &8220;fire ant colonies vary in size, but a mature, 3-year-old colony typically contains 250,000 workers, which are sterile females, and hundreds of reproductive males and potentially reproductive females. In addition to single-queen colonies, many have multiple queens, increasing tenfold the number of mounds in a single acre.&8221;

Worker ants are very protective of their queen and will do anything necessary to keep her safe. When a colony is disrupted, the workers immediately take action to relocate the queen to a secure site. The survival of the colony is dependent on the queen.

&8220;Therefore, the best control is not a method that will merely kill workers but bait that will be taken back to the nest by foraging ants where it will either kill the queen or render her sterile. Baits combine a food to attract the ants with an insecticide or insect growth regulator (a pesticide that works by disrupting the ants&8217; reproductive system). Although baits are slow acting, they are often the best way to reach the queen and eliminate the colony. If mounds are in a heavily used area, one method of treatment is to broadcast a bait product, followed in 3-5 days with a contact insecticide applied directly to each mound (dust, drench, granular, etc.),&8221; according to USDA entomology specialists.

Mississippi State University entomologists recommend using a broadcast application of a bait product for management. &8220;In this method a seeder or spreader is used to scatter the bait in a uniform pattern over the infested site. The treater should measure the length and width of the property in order to determine the amount of product to use.&8221;

Because &8220;hot dry weather tends to push ants deeper in the mound,&8221; making them harder to control, &8220;apply one to two bait applications four weeks apart during the spring and early summer.&8221; Don&8217;t treat the area if rain is expected in the next few hours. MSU entomologists also suggest &8220;the more people who treat in a given area, the better. For example, if you are the only person in your area treating, ants from untreated property will continue to infest your property. An &8220;additional bait application in late September or early October is also recommended. This application should contain a growth regulator type treatment.

Keep in mind that baits are not labeled for use in a vegetable garden, but can be used in areas six to eight feet from the edge. &8220;Baits can be used in lawns, picnic grounds, cemeteries, parks, school grounds, athletic fields, etc.&8221;

Get your neighbors involved in fire ant management by setting a date this fall when everyone can treat their own property. Chip-in so that you can buy the bait material in bulk. A handheld seeder or spreader can be purchased for as little as $25, and can be shared.


According to MSU research, the annual cost for the above program (including the optional treatment) is, &8220;At $13.00 per pound and 10,000 square feet of treated surface, the cost would be $4.47 per bait application. Three bait applications would cost $13.41 per year, or if the optional treatment is excluded, the cost would be $8.94 per year for bait applications. One or two dollars could be added for additional drench applications if they are needed. These estimates are based on a &8220;do-it-yourself&8221; treatment and does not include any charges for labor or equipment. Of course, if a professional service is used, the costs will be higher.&8221;