Bug of the Week April 27, 2009

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Each spring without fail my home is invaded by small dark brown ants called odorous house ants. The odorous house ant gets its name by virtue of the distinctive smell it makes when you crush one between your fingers or on a counter. The odor is reminiscent of slightly fermented coconuts. I discovered the vanguard of this year’s expeditionary force on a Tuesday evening as a few adventurous scouts explored my kitchen counter. By morning, a steady stream of ants formed an uninterrupted column from an unknown stronghold somewhere beyond my patio door, up the kitchen wall, across the counter, and through a seam deep into the cupboard. Dozens of workers followed the invisible chemical trail deep into my cupboard where some delightful treat was consumed and transported back along the ant trail to other nest-mates waiting in the colony. After spending the chilly months of winter and early spring in a state of relative inactivity, with the return of warm weather, worker ants conduct an unending search for sugars, proteins, and fats to feed the burgeoning colony. In the wild, these foods are provided largely by plants and other insects. When ants locate a rich source of food, such as the sugary honeydew produced by a colony of aphids, they establish a trail marked by chemicals called pheromones. The trail leads other workers from the nest to the bounty. Outside odorous house ants nest beneath stones or fallen logs. I usually have several colonies in my woodpiles. However, they are very opportunistic and will occasionally enter homes to set up shop. I have discovered colonies of these rascals in my wall voids and in electrical appliances including a surge protector beneath my desk. Their quest for food brings them into homes and a few grains of sugar on the counter, a pet dish on the floor, or a leaky bottle of pancake syrup in the pantry, will often initiate a full scale invasion by searching workers. If you find ants and their telltale trails on counters or along baseboards, try to locate the source of food and then follow the trail back to the point of entry into your home. In my home, this was a small crack where the sliding patio door joined the exterior wall. To foil these raiders, first eliminate as many sources of food as possible. Clean the counters, mop up drips, and get pet food off the floor. Be sure that no syrup or sweets are spilled or leaking in your cupboards. Ant trails on the counter or floor can be disrupted by spraying them with household cleansers or other solutions. You can buy ant traps or purchase tubes of liquid or gelatin ant baits. Place ant traps or baits at locations indicated on the label. I usually place one near the point of entry to my home and several others around my counters and near their raiding columns. The traps and baits contain a lure that attracts ants searching for sweets or fatty foods. The lure contains poison. Workers ingest the toxin and are killed or in some cases they carry the toxic treat back to the colony and feed the deadly meal to the queens and their nest mates and, voilà, the royals are assassinated and the colony with them. A few well placed bait stations in my kitchen put an end to the ant trails in a matter or days. To be effective, the bait must attract ants. If you purchase a bait or ant trap, and the ants eschew your invitation, well, get yourself another type of trap. Whenever you use a product containing an insecticide, be sure to precisely follow the instructions on the label. Never apply pesticides directly to surfaces used for food preparation or consumption like countertops or tables. Many species of ants can become visitors or residents in our homes. Large black ants in the home, especially ones with wings, may be carpenter ants and a sign of more serious problems than just a little sugary larceny. If you have concerns or questions regarding the identity or management of any six-legged vandals, contact your local extension office for advice.

To learn more about ants inside homes, please visit the following web sites.

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