When ants move in: Odorous house ants, Tapinoma sessile

Last week with the return of summer weather here in the DMV, it wasn’t just periodical cicadas that amped up activity. When Mother Nature turns up the heat, other cold-blooded insects resume their quest for food and shelter. My personal home invasion began on a warm day last week when legions of foraging worker ants laid down a trail from my patio door, along the baseboard, and up the wall to a drop of syrup on the kitchen counter. Odorous house ants have become a perennial guest at Bug of the Week. These small brown ants invade homes throughout our region each spring. This ant earns its name by virtue of the distinctive smell it makes when crushed between your fingers or on a counter. The odor is reminiscent of slightly fermented coconuts. 

How and why does this invasion recur each year? After spending the chilly months of winter and early spring in a state of relative inactivity outdoors, with the return of warm weather, worker ants conduct an unending search for sugars, proteins, and fats to feed hundreds of hungry mouths in their burgeoning colony. In the wild, plants like my peony and other insects like the aphids on my peony provide these foods. When ants locate a rich source of food, such as the sugary honeydew produced by a colony of aphids or scale insects, they establish a trail marked by chemicals called pheromones. The trail leads other workers from the nest to the bounty. 

With the return of summer-like weather, odorous house ants can be found outdoors foraging at floral nectaries like those on a peony. Honeydew produced by phloem feeding insects like aphids is an irresistible source of food for ants. When sweets drip on countertops, scouts recruit other workers and a full-blown home invasion can ensue.  Baits laced with insecticides can foil ant invasions as one by one, workers collect the toxic treat, return to the colony, and poison their nestmates.

Outdoors, odorous house ants nest beneath stones or fallen logs. I usually have several colonies in my yard in a woodpile or under stones in a wall. However, odorous house ants 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. 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 after your pets have eaten. 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. 

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 along with them. A few well-placed bait stations in my kitchen put an end to the ant trails in a matter of days. To be effective, the bait must attract the ants you want to control. If you purchase a bait or ant trap, and the ants eschew your invitation, well, get yourself another type of trap or bait.

Whenever you use a product containing an insecticide, be sure to follow precisely 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 the local university extension office in your county or state for advice.

This post appeared first on Bug of the Week