White-footed House Ants

Brief:

The white-footed ant, Technomyrmex difficilis, is part of an Old World species group, several of which have broad distributions, resulting in numerous misidentifications. The white-footed ant is a medium small (2.5-3 mm long), black to brownish-black ant with yellowish-white tarsi (feet) and a one-segmented waist, they have five abdominal segments, 12-segmented antennae, few erect hairs, and no sting.

The white-footed ant looks similar to the Argentine ant, Linepithema humile, however, the petiole of the Argentine ant has a vertical projection that is lacking on the white-footed ant.

Habits

Although white-footed ants are strongly attracted to sweet foods they will also feed on dead insects and other protein. They are commonly found foraging along branches and trunks of trees and shrubs that have nectars and/or sap-sucking insects that produce honeydew. They tend to send many foragers from their nests to search for new food resources. Nestmates are recruited to resources by foragers who lay trail pheromones. Often the same trails are observed between a nest and resource for months at a time. In and on structures, foragers tend to follow lines, such as an edge of an exterior wall panel, which eventually leads to some small opening to the interior, where foragers that enter become more noticeable to occupants. Frequently, the white-footed ant finds its way inside wall voids where they follow electrical cables and emerge into various rooms, especially kitchens and bathrooms, where liquid and solid foods can be encountered resulting in heavy trailing activity.

Habitat

The white-footed ant nests at or above ground level in numerous locations within the landscape and home. Nests are frequently found in trees and bushes, tree holes, under palm fronds and old leaf boots, under leaves on trees, in loose mulch, under debris, in leaf-litter (both on the ground as well as in rain gutters), wall voids, and attics. Nests tend to be found outside of structures more than inside. Preferred nest sites provide proximity to moisture and food sources, and protection from predators and environmental extremes. Numerous nests can be said to constitute a colony, but since all neighbouring colonies seems to be interconnected, there is probably no way to delineate the limits of a single colony.

Threats

Prevention

The white-footed ant is an extremely difficult pest to control due to the large size of its colonies, but control can be achieved. Baits are effective for many sweet-feeding ant species. No surface or residual treatments with liquid insecticides have yet been found to be effective for controlling these ants. Management has only been accomplished by treating infested homes exclusively with baits containing borates. It is critical that all populations of white-footed ants on the property being treated are identified so that baits can be made available to each population. Since liquid baits tend to slowly dry out, it is important that fresh baits are always available until the target population has been controlled. Although bait toxicants may not be orally transferred between workers, they can still kill enough workers to cause death of brood by starvation. In addition, it is also thought that very slow acting bait toxicants may, with time, end up in the trophic eggs. Residual and systemic sprays to vegetation surrounding structures can also help by eliminating honeydew-producing insects.

Infestations can frequently be treated by placing liquid baits along trails on the exterior of a property.

A key aspect of white-footed ants control involves trimming trees and shrubs surrounding the structure to stop ants from ‘bridging’ (trailing from the vegetation onto the structure). The best policy is to not have any vegetation touching exterior walls. Placing liquid baits at the base of these trees or along branches can also be helpful. Ant trails coming from neighbouring properties via adjoining vegetation, fences, or across lawns, must also be treated.

Others

Some photos and information are provided by Bayer.

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