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Description and Biology

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Larger yellow ants, Acanthomyops interjectus, are about 1/4 inch long (workers) and are yellow to yellow-orange. Queens are 3/8 inch long and are darker brown. Before founding a nest, queens have wings and resemble small wasps. Once in the new nest, queens shed their wings and begin to rear workers. The larger yellow ant is interesting because it secretes citronella when crushed or disturbed. Perhaps not noticeable with only one ant, but when a nest is disturbed, the odor of citronella may be noticable. Although the larger yellow ant does not sting, it does use formic acid for defense against other insects. Apparently the citronella helps the formic acid penetrate through the integument of the insect with which the ant is contending. These ants nest in open areas and form large mounds in soil, under logs, rocks, patio blocks, porches, and concrete patios. They often mound up large amounts of soil as they excavate their galleries. Larger yellow ants swarm most of the year although winged forms usually occur in in the fall or winter, and they usually swarm at night. Swarming may even occur inside buildings when colonies are located next to or under the structure! Winter is the normal time for new colonies to be founded.

larger yellow ant

The larger yellow ant has only one node between the thorax and gaster.

Larger yellow ant worker

Larger yellow ant workers have very small eyes and a ring of microscopic hairs at the very tail end/

Larger yellow ants usually swarm

Larger yellow ants usually swarm during the night.

queens have wings

Larger yellow ant queens have wings they shed later in their new nests.

Larger yellow ant queens are darker and larger than their worker

Larger yellow ant queens are darker and larger than their workers.


Larger yellow ants sometimes excavate an impressive amount of soil as they expand their nests.

Larger Yellow ants feed primarily upon honeydew excreted by aphids and mealybugs that feed on roots as well as other hapless insects they overcome. They even transport aphids and mealybugs to new plants as previous plants dieback and not longer produce sap. Larger yellow ants are primarily nocturnal and are usually not seen during the day. When encountered, workers are swift, agile, and timid. They retreat into the nest readily.

Residential Recommendations

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Control of larger yellow ants is not critical, since they cause little damage other than the annoyance of the appearance of their nest mounds in the landscape or their rare presence indoors. If the colony is in the landscape, drench the colony with diluted insecticide, labeled for this purpose. Baits are not effective for this species. Ants found indoors can be vacuumed or swept up and discarded.

Other Resources

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For assistance with a specific problem, contact your local Cooperative Extension Center.

This Factsheet has not been peer reviewed.


Professor Emeritus
Entomology & Plant Pathology

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Publication date: May 13, 2020
Revised: May 13, 2020

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