The slender twig ant (Pseudomyrmex gracilis) is a non-native ant species that has become prevalent in the southern half of the Gulf Coast states where it is considered a pest in urban and suburban areas. This ant species establishes nests in tiny cavities within plants and trees on the ground and at elevated locations. Nests are most frequently found within hollow twigs, branches, plant stems, grass blades, in wood cavities that had been previously excavated by carpenter ants and termites, and in crevices and door frames in homes and buildings.

Slender twig ants (STA) live in small single-queen colonies, and they feed on insects, fungal spores, and tend aphids for sweet-tasting honeydew. These ants are highly protective of their plant hosts, and workers will not hesitate to emerge from their nest to attack humans en masse if the ants perceive a threat to the plants that they inhabit. The stings inflicted by these ants are extremely painful, and nests located in high-traffic areas like door frames should be promptly destroyed for this reason.

Although the STA was first recorded in the US back in 1960 when colonies were recovered from the coast of southern Florida, this species has only recently established a sizable population in New Orleans and Houston. STAs are not well understood by urban entomologists and the species demonstrates a variety of peculiar habits that are not characteristic of social insects, such as workers not following fixed foraging trails. This makes it virtually impossible for STA nests to be pinpointed, and there currently does not exist any specific program for STA control. At the moment, the STA’s status as an invasive species in the US is still uncertain, but this species’ status as a medically significant nuisance pest of structures and urban and suburban landscapes is well established. STA workers are easy to recognize due to their noticeably large and elongated body that is brownish-orange in color.

Have you ever encountered an ant nest within your home?