Who Invited the Ants?

Who Invited the Ants?       ant 2

Tara A. Spears

Blame it on El Nino for causing another warmer than average winter. Although it is just the beginning of our sub-tropical summer, this is the third swarm of the tiny sugar ants this year. These miniscule marauders are in my flower beds, along the patio, and in the house. These prolific insects are small enough to pass through screens. In order to try to eliminate these pesky insects, I followed the trail from the window through a room and up the wall to find them nesting behind a hanging picture frame. Argh! I spent an entire day taking down every picture, treating the back with poison, rehanging.

The ghost ant, Tapinoma melanocephalum, is considered a nuisance ant. It is believed that this species originated in Africa or the Orient but it is so widely distributed by commerce -hitching a ride from one country to another in shipping cartons or produce.  Ghost ant workers are extremely small, 1.3 to 1.5 mm long and monomorphic (one-sized). All of the photos in the article are greatly magnified: you can’t tell the body shape with the naked eye.

The ghost ant is highly adaptable in its nesting habits. It nests readily outdoors or indoors. Colonies may be moderate to large in size containing numerous reproducing females (polygyny). Generally, the colonies occupy local sites that are too small or unstable to support entire large colonies. The sites include tufts of dead but temporarily moist grass, plant stems, and cavities beneath detritus in open, rapidly changing habitats.

  Indoors, the ant colonizes wall void or spaces between cabinetry and baseboards. It will also nest in potted plants. Thus, the colonies are broken into subunits that occupy different nest sites and exchange individuals back and forth along odor trails.  Research in the late 1990s reported that ghost ants are opportunistic nesters in places that sometimes remain habitable for only a few days or weeks.  Nevertheless, even if the ants swarm in your kitchen cabinet for a week, the sheer numbers of ants are aggravating and unappealing.  

ant 1Multiple queens may be spread out in multiple sub colonies. Usually, nesting occurs in disturbed areas, in flowerpots, under objects on the ground, under loose bark, and at the bases of palm fronds. Indoors, the ant nests in small spaces such as cracks, spaces between books, or wall voids. Indoor foragers often come from outside, as with my trail through a screen. This is a very common pest inside homes.

Control and Prevention:  The best approach to ant control in the home is cleanliness. Any type of food or food particles can attract and provide food for ants. It’s best to store food in tight containers. Remove plants that can attract ants or control aphids, whiteflies and other insects that produce honeydew. Reduce moisture sources, including condensation and leaks as the ants can invade during the dry season in search of water.ant 7

If possible, follow the trails of this species back to the nest and treat the nest. If treating the trails with bait check within one or two days to see if the ants are feeding. If not, relocate the bait or try another ‘attractor’. Indoor colonies nesting within voids can be controlled with baits. Access of foragers entering from outdoors through cracks and crevices or screens should be restricted with barrier sprays.

Generally, ant control is not necessary except where it becomes a nuisance in the home or in greenhouses. If control is necessary, the ghost ant is susceptible to a number of insecticides used in baits or as contact poisons. There are many effective commercial products available but I have made my own for more than 20 years.

ant 3ant 4ant 5


DIY Ant Killer

1 cup of sugar; 1/2 cup of water; 1 Tablespoon of Borax cleanser or 1 teaspoon of boric acid

Mix it all together and you’re ready to take action. Put some of the mix into empty lids or soda bottle caps; place the mix where you have seen ants. You might want to put a drop of jelly or honey outside the lid to really attract the ants to the bait. Once the ants come, they will have a feast and take the mix back to the nest.

Using homemade boric acid/borax ant killer isn’t an immediate fix for an ant problem. It’s a slow-acting poison, and each ant that takes it back to the colony shares it with only a few other ants. It might take a while for the poison to reach the queens, which can effectively kill the colony. It should take only a few days for you to notice a reduction in the number of ants near the bait, but it could take three to four weeks to completely eradicate the colony causing your problems. Change the bait every few days to keep it fresh. I just find this mix does the job with less harmful chemicals than the commercial products.

The next time the ants invite themselves into your home, try some of the DIY mix. Since most ants are scent driven, wiping down your kitchen counters or food prep areas is also a great non-poisonous ant repellent.

ant 8