Citronella Ant

The citronella ant, Lasius interjectus (Family: Formicidae, Subfamily: Formicinae), is a subterranean species. Workers are typically monomorphic, ranging from 3.5-5.0 mm in length, and are characterized by a yellowish-brown to reddish-brown coloration. They possess a distinct citronella-like odor when crushed, attributed to defensive compounds (citronellal and geraniol) produced in their mandibular glands. Queens are significantly larger than workers, reaching up to 8-9 mm, and are typically darker. Males are alate and smaller than queens. This species undergoes complete metamorphosis (egg, larva, pupa, adult). Colonies are subterranean, often very large (tens of thousands of individuals), and typically monogynous, although polygyny can occur. Nuptial flights usually occur in late summer or early autumn, often after rain events, when alates emerge in large numbers. Developmental timings are poorly documented but are likely similar to other Lasius species.

Lasius interjectus is primarily subterranean, foraging almost exclusively underground or under objects, making surface foraging uncommon. Their diet consists almost entirely of honeydew secreted by subterranean root-feeding aphids and mealybugs, which they actively tend and protect. They rarely forage for other food sources and are not typically attracted to human foods. When disturbed, workers emit a strong citronella odor as a defensive mechanism. They are generally not aggressive but will bite if threatened. Alates are attracted to light and often emerge in large numbers during their nuptial flights, especially in the late afternoon or early evening, a primary point of human interaction with this species.