Lasius interjectus

Mayr, 1866

Larger Yellow Ant, Larger Citronella Ant, Citronella Ant

Lasius interjectus, commonly known as the larger yellow or larger citronella ant, is a North American ant distinguished by its yellowish coloration and distinctive lemon-citronella scent. Formerly classified in the Acanthomyops (now a subgenus of Lasius), this species nests in soil, often along building foundations, and is known for producing swarms that sometimes emerge indoors. The species poses no structural threat to buildings and is recognized by its chemical defense using citronellal and formic acid.

Lasius interjectus by (c) Bill Keim, some rights reserved (CC BY). Used under a CC-BY license.

Lasius (Acanthomyops) interjectus arizonicus by the Smithsonian. Used under a CC0 license.

Lasius (Acanthomyops) interjectus californicus by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Lasius interjectus: //ˈleɪsiəs ˌɪntərˈdʒɛktəs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from by: elbowed (geniculate) versus bead-like; narrow petiole versus broad waist joining and ; forewings larger than hindwings with few versus four equal-sized wings with many fine veins. Distinguished from carpenter ants (Camponotus pennsylvanicus) by smaller size, yellow-reddish color versus black-dark brown, and citronella odor. Distinguished from other Lasius by larger size and specific citronella scent profile.

Images

Habitat

Nests in soil, commonly along building foundations, under concrete slabs, and in crawl spaces beneath structures. Outdoor nesting occurs in ground soil. Does not nest in wood or cause structural damage.

Distribution

Native to the United States. Documented from the eastern and central United States including the DMV area (DC-Maryland-Virginia), with specific observations of December swarming in Maryland.

Seasonality

swarming observed in late autumn through early winter (December) in the mid-Atlantic region; unusual timing compared to typical warm-season swarming. This winter swarming pattern distinguishes it from spring-swarming in the same region.

Diet

Feeds on honeydew produced by root-feeding aphids and mealybugs; tend these hemipterans and move them between plant roots to optimize honeydew production. Also hunts soft-bodied prey.

Host Associations

Aphids - mutualismTends root-feeding aphids, moving them between plants to maximize honeydew production
Mealybugs - mutualismFeeds on honeydew produced by mealybugs

Life Cycle

Colony occurs through production of winged (queens and males) that emerge from nests to mate and establish new colonies. Swarming events can last several days. Newly mated queens attempt to found colonies independently. are sterile females supporting the colony.

Behavior

Defends colony by releasing citronellal (lemon-scented ) from mandibular glands when threatened, alerting nestmates. Can spray formic acid from abdominal glands as chemical defense against . exhibit herding , actively moving aphids between plant roots. emerging indoors attempt to exit toward light and outdoor environments.

Ecological Role

Functions as a hemipteran-tending , facilitating and mealybug through protection and transport. Serves as prey for ant- . Chemical defenses (citronellal, formic acid) demonstrate aposematic and allomonal functions in interactions.

Human Relevance

Considered a nuisance pest when swarms emerge indoors from nests beneath slabs or in crawl spaces, but causes no structural damage. Often mistaken for or carpenter ants, causing unnecessary concern. Can be managed by vacuuming indoor ; outdoor colonies along foundations can be treated with labeled . Not attracted to baited traps.

Similar Taxa

Reticulitermes flavipes (Eastern Subterranean Termite)Winged forms similar in size and swarming ; distinguished by ' bead-like , broad waist, and equal-sized wing pairs with many versus features
Camponotus pennsylvanicus (Black Carpenter Ant)Both may swarm indoors; distinguished by carpenter ants' larger size, black-dark brown coloration, lack of citronella odor, and wood-nesting
Lasius (Acanthomyops) spp. (other citronella ants)Share citronella scent and yellow coloration; L. interjectus distinguished by larger size as implied by

Misconceptions

Frequently mistaken for destructive or carpenter ants due to indoor swarming of winged forms, leading to unnecessary extermination calls. Does not consume wood or damage building structures despite nesting near foundations.

More Details

Taxonomic History

Formerly placed in Acanthomyops, which is now treated as a subgenus within Lasius based on phylogenetic studies. Described by Gustav Mayr in 1866.

Chemical Ecology

Produces citronellal (the same compound found in lemongrass and citronella plants) as an ; also produces formic acid as a defensive secretion. These compounds are not related to the citronella plant but represent convergent chemical evolution.

E.O. Wilson Connection

E.O. Wilson studied citronella ants (Lasius spp.) in Rock Creek Park as a youth, which contributed to his lifelong passion for myrmecology and development of as a model for understanding social evolution.