   Managing Household Ants - July 26, 2000 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County In our gardens, ants are often found tending aphids, scales, whiteflies, and mealybugs while harvesting their honeydew (the sweet, sticky substance they secrete). Some species, including carpenter ants, destroy wood and/or collect plant litter. Others invade our homes and live off our food. There are over 12,000 species of ants throughout the world. To narrow the field, this column will focus on household ants: in particular, the odorous house ant (Tapinoma sessile). Ants, like their relatives, bees and wasps, are social insects that go through stages of complete metamorphosis: egg, larva, pupa, adult. Adult ants serve different functions within the colony. Queen ants are the largest in the colony and lay the eggs and sometimes feed and groom the larvae. Sterile female workers gather food, tend the larvae, build tunnels, defend the colony, and are the most numerous within the colony. Male ants do not participate in colony activities and their only apparent purpose is to mate with the queens. They are relatively few in number and cared for by the female workers (any resemblance to human beings is strictly coincidental). A single, newly mated queen typically establishes the colony. She lays eggs, feeding the hatched larvae her own metabolized wing muscles and fat bodies until they pupate. Several weeks later, the pupae transform into sterile female adult workers, and the first workers dig their way out of the nest to collect food for themselves, for the queen (who continues to lay eggs), and for subsequent broods of larvae. As numbers increase, new chambers and galleries are added to the nest. After a few years, the colony begins to produce winged male and female ants, which leave the nest to mate and form new colonies. Odorous house ants are 1/8" to 1/4" inch long, blackish, brown in color, and often invade a home by the thousands following a change in the weather. They also have a distinct smell when crushed that some people say is similar to rotten coconut. Odorous house ants usually have their nest outside of your house near a shrub or mulched area and enter through a crack in the wall, window, or foundation. They typically feed on sweets, meats, and dead insects. Scout ants (female workers) wander in search of food. Once food is located, she takes a short, direct route home. While returning, she also leaves an odor trail. Upon reaching the nest, she alerts her nestmates of the food source and they all follow the odor trail directly to the food source. This phenomenon is called trailing. Trailing ants can be closely observed and this behavior can be exploited in their control. The first strategy should be exclusion. Look at the trail location and seal the cracks, caulk the seams, and use other materials to limit their entry. This is easier said than done due to the small size of this pest. Next, scrub trails with detergent to remove the scent (pheromone) trail and spray a residual insecticide (such as carbaryl or diazinon) on the trail if desired. The nest can also be treated if it can be located. Toxic baits can also be employed. The toxins in the baits range from environmentally friendly boric acid to synthetic insecticides. The bait itself can be tricky too. Ants have varied diets that may or may not include sugars, fats, and proteins depending on the state of the brood and other colony needs. To bait successfully, the toxin must be transported back to the colony and ingested by the queen as well as the others. If toxic baits are used, do not use insecticide sprays. This will not allow effective transport of the toxin back to the colony. Please remember to follow label directions on any products you decide to use. The University of Arizona Cooperative Extension has publications and information on many insects and plant diseases. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. The Yavapai County Cooperative Extension web site is http://ag.arizona.edu/yavapai/. |