Winged ants in house

Asked November 25, 2019, 8:55 AM EST

Hi, for a few days now I have seen black ants, some winged, some without wings, in my house. They are very slow moving. They are in a corner where I see smaller ants in the spring, but their activity usually disappears by the summer. These ants are larger, about 10 mm and very black. I am concerned that they are carpenter ants. I have laid out bait for carpenter ants, but they don’t seem to be interested in feeding at all. Can you please direct me to an expert who can identify the ants and also to someone who could help me treat the problem? I have frozen a few specimens and I am uploading some photos as well. Thank you very much, Gabriele Mayer

Ingham County Michigan

1 Response


Those look more like winged acrobat ants, Crematogaster species (Hymenoptera: Formicidae).

Acrobat ants get their common name from their habit of raising their abdomen over their head and thorax. The workers are known to bite aggressively and to give off a repulsive odor when alarmed. In nature, colonies may nest in exposed soil, under stones, stumps and old trees. They occasionally become pests by invading homes where they are known to nest in woodwork and foam insulation, and infest household foods. They feed on live and dead insects, and they tend aphids for their sugary excrement known as "honeydew." In homes, they show a slight preference for sweets and meats or other high protein foods.

Winged forms or reproductives usually appear in the fall of the year. When these appear inside homes, it is a good indication there is a nest of acrobat ants located inside the home.

The best method of controlling acrobat ants in the home is to locate the nest and treat in directly with a persistent insecticide labeled for indoor use like Ortho’s Home Defense Max. If the nest cannot be located, poisoned bait may offer some help in reducing their numbers. Baits are less effective when used during the summer months when the ant’s favorite foods are plentiful. Baits can be purchased at If the ants are coming in from the outside then spraying all possible entry points on the outside of the building (where sills and foundations meet, around doors, windows, vents and utilities) with fipronil (sold as Termidor SC). Fipronil forms a non-repellent barrier that the ants cannot detect. They pick it up and spread it through the colony. Termidor is not widely available but it can be purchased over the internet or at John Deere Landscaping (formerly Lesco’s). Termidor is not labeled for use inside homes and other buildings.

Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.