Yellow Ant

Introduction

Yellow ants [Lasius (Acanthomyops) spp.] belong to the family Formicidae in the order Hymenoptera. They are sometimes called citronella ants because of their distinctive lemonlike odor.

Description

Yellow ant workers are small, 4 mm (0.06 inch) or less in size, and yellow to yellow-orange color (Fig. 1). Their bodies are robust and somewhat shiny. Queens are larger and often darker colored.

Habitat

Yellow ants are largely subterranean and often go unnoticed until they swarm. They nest in moist soil, under rocks, or in decaying wood. Their colonies may be close to houses, but they rarely enter houses in search of food. Yellow ants largely avoid light except when swarming.

Life Cycle

Yellow ants have a complete life cycle of egg, larva, pupa, and adult stages. Like other ants, yellow ant colonies have a complex social structure of sterile workers and a fertile queen, with winged reproductives produced for establishing new colonies. The worker ants raise the ant brood, gather food, maintain the nest, and take care of the queen. The queen lays eggs, producing both worker ants and fertile male and female ants that have wings as adults. These winged reproductives fly from the colony in spring and fall to mate and start new nests elsewhere. More than one colony in an area may swarm at the same time, producing thousands of winged ants.

Lasius claviger, the smaller yellow ant, is a social parasite of other yellow ants. Mated queens will sneak into the nests of related species of Lasius, kill the established queen, and take over the colony.

Distribution

Yellow ants are common in Virginia and can be found throughout much of the United States.

Damage

Homeowners are often alarmed at large masses of winged yellow ants that may appear unexpectedly around the outside of houses. These swarms are often associated with sidewalks, patios, concrete slabs, and foundation walls, but sometimes they show up in basements. Yellow ant colonies are found in these locations, but go unnoticed for most of the year until they swarm. Homeowners may mistake the swarming yellow ants for termites, but yellow ants are not structural pests and they do not damage wood.

Control

Yellow ants do not invade houses often, even though they may nest next to the foundation. If found indoors, swarming yellow ants found can be killed with a fly swatter, vacuumed up, or treated with an aerosol insecticide. If ants emerged inside the home through a crack in the foundation or a hole in a wall, thoroughly caulk the opening to limit their future entry. Yellow ants typically do not respond well to baits. If control is necessary, treat the nest directly with liquid insecticide.

Revised

Theresa A. Dellinger, September 24, 2021.