Another Ant Abounds

The dark rover ant, Brachymyrmex patagonicus, is causing great concern in many areas of Texas this year. This ant is believed to be native to South America, but it has now relocated and established itself in the southern United States. Outside rover ants may be seen running up and down on blades of grass, chairs, fence posts or any other objects in the yard very quickly.

The female swarmer ants (the winged ants) are 3/16 inches in length and brown in color. These swarmers will take flight just after dusk and are attracted to lights. The female swarmers are usually noticed the next day when a large number are floating in swimming pools. Their enlarged abdomen will appear to be striped. The male swarmers are very small compared to the female swarmers and some reports state that the males can fit through the tiny openings in mosquito screen. The worker ants can be more troublesome, since they can be found in a variety of indoor sites. These worker ants are 1/16 inches in length and are dark brown or reddish brown in color. For identification purposes, Brachymyrmex patagonicus have one node and 9 segmented antennae.

Rover ants are honeydew feeders, feeding on secretions from aphids, scales and other sap-feeding insects. Rover ants are commonly found in woods and other natural settings, as well as around buildings. Outside they will tend to nest in soil, mulch or other decaying wood. In buildings, they prefer areas with high moisture so they are usually found in bathrooms or where leaks occur in the plumbing.

Some Control Options:
The dark rover ant has a single queen within a colony but there can be many colonies in an area. This makes a large infestation within a building very hard to control.

Some Non-Chemical Control Options:
1) Find and seal small holes or cracks.
2) Treat nearby trees and shrubs to decrease the amount of sap feeding insects such as aphids and scales. This will reduce the amount of honeydew that can be consumed by the rover ants.
3) Prune limbs of trees and shrubs so that they do not touch the buildings. This will prevent easy access into the buildings.

Some Chemical Control Options:
Control can be found using a combination of baits and sprays. Some insecticidal sprays that can be used involve a combination of active ingredients such as those containing a pyrethroid and a neonicotinoid. Gel and liquid baits are also suggested to be used outdoors and indoors. This is a persistent ant so patience is needed for successful control.

Photo of rover ant swarmer. Photo by Micheal Merchant, Extension Entomologist and Professor, Texas AgriLife Extension, Texas A&M University System.