The two-spined trap-jaw ant (Odontomachus haematodus) is a large, predatory ant species found throughout much of South America. First detected in Mobile in the mid-1950s, this species has established populations along parts of the Gulf Coast and southern Alabama over the past few decades. Thankfully, its range in Alabama and the Southeast remains limited, and there are steps that can be taken to reduce its spread.

Causing Problems

The two-spined trap-jaw ant poses several problems. It is aggressive, has a potent sting, and regularly nests around human habitation. This creates risks for people with allergic reactions and can make gardening or other outdoor maintenance uncomfortable and tedious.

The species also displaces native ant species. In some areas completely replacing native carpenter and funnel ants. It is a fully carnivorous ant species, with large numbers of this aggressive exotic surely influencing small invertebrate populations where it occurs.

Identification

While relatively easy to identify, this species is commonly mistaken for large native ants like carpenter ants. Thankfully they have several distinguishing characteristics.

Size: They are easily distinguished from most native ants by their size. Workers are approximately half an inch in length.

Coloration: Workers and queens are a glossy black color, while the males (which resemble small wasps) are a tan-brown coloration.

Build: Compared to native ants of similar size, they are slender in build and have an angular, almost sculptured appearance. The abdomen (rear of the ant) is sharp and pointed. They have long, wide jaws that snap with great force.

Sting: It stings readily, unlike similar native ants.

Nest: The trap jaw ant nests under logs, at the base of buildings or other structures, and among the roots of trees. Loose, coarse piles of debris are often present around the entrances. Colonies are small compared to similar native ants, rarely holding more than a few hundred workers.

Action Steps

This species is currently localized to only Mobile, Baldwin, and possibly Escambia Counties in Alabama, as well as parts of Florida, Mississippi, and Louisiana. Rising temperatures and suitable habitat nearby make it likely that the species will continue to spread. To mitigate this, there are several potential action steps.

• As with any invasive species, it is recommended to report suspected sightings of this species to your local Extension agent, EDDMapS, or iNaturalist.
• Take care when moving potted plants, compost, rotted wood, or other potential nesting sites from infested areas to areas the trap-jaw ant is not yet present.
• As active hunters, traditional ant baits and granular poisons are less effective on trap-jaw ants. Direct application of pyrethroid insecticides to nests and the immediate surrounding area can eliminate a colony. Use only as directed on the packaging.