Moisture Ants

Facts, Identification & Control

Latin Name

Lasius spp.


Workers are 4 to 4.5 mm long and yellow in color. When crushed, they produce a lemon scent that is often described as citronella.

moisture ant picture

Behavior, Diet & Habits

Moisture ants get their name from their habit of nesting in high-moisture areas. Some people call them yellow ants because the workers are yellowish in color. There are several species in the United States. One of the largest species is Lasius interjectus (Mayr), also known as the citronella ant.

Moisture ants are common from the Pacific Northwest to New England. Their range extends southward to Florida and Mexico. Outdoors, they often nest under rocks or logs. They sometimes nest above the ground in rotting logs. Moisture ants feed on honeydew. The workers get honeydew from aphids and scale insects that feed on plant roots. Moisture ants often tend aphids to collect the honeydew that they produce. Some moisture ant colonies make their nests against the foundation of homes. When colonies are under slabs, the ants often push soil up through cracks in the concrete while they are digging galleries underneath. When this soil appears in basement floors, it can cause distress for the homeowners. Many people mistake this soil for a sign of termite activity.

When moisture ants move indoors, they often nest in wood that is moisture damaged. They frequently find damaged wood in areas like bath traps. They sometimes nest inside walls where there is a plumbing leak. There have been cases of these ants nesting in damp soil in crawlspaces. In these situations, the workers made mounds of excavated soil in the crawl space.

If the ants have nested in damp or damaged wood, correcting the moisture problem and replacing the wood will be a priority. In damp or humid areas, treated wood may be a good replacement.


Each colony has a single queen that generates the colony’s members. Mating occurs when winged males and females, called swarmers, swarm from the colony in the summer. Mated females go on to found new colonies.

Signs of a Moisture Ant Infestation

The most obvious signs are the yellow workers or the swarmers.

Do Moisture Ants Fly

Moisture ant is a common name that most frequently includes ants in the genus Lasius. The only members of a moisture ant colony that fly are the female and males who participate in mating swarms.


If winged ants have swarmed inside the home, remove them with a vacuum cleaner. Empty the vacuum bag promptly and take it outside to the trash. It is sometimes hard to tell whether winged insects are ants or termites. Call the local pest control professional for an inspection and identification.