When I came home from work earlier this week, my front walkway was covered in winged ants (referred to as alates). They were crawling on the bricks, the timber border, the solar-powered perimeter lights, and the nearby vegetation. Closer inspection revealed that in addition to the larger, darker winged ants, there were also clusters of tiny yellow ants on the ground. Although different morphologically, both are the same species of citronella ants, likely Lasius claviger. The smaller yellow individuals were the workers milling about what I presume were the openings to their underground colonies, and the larger winged individuals were the new queens. Mating flights for this species occur relatively late in the season, and are most commonly reported in late September or early October (so my ants are right on time!). The queens will mate and then spend the winter sheltering under rocks or wood, emerging again in the spring to start a new colony.

Citronella ants get their name from the lemony or citronella-like odor they emit when threatened. It is most noticeable when the ants are crushed. I can attest to this, as I once had someone convince me to taste one – when crunched, it did indeed taste and smell lemony. 

These tiny yellow ants are very common in the eastern United States and can sometimes be confused with termites if they swarm into homes. Unlike termites, however, the citronella ants pose no harm to your structure. They prefer to build subterranean colonies under rocks or stumps where they tend root-feeding aphids to collect the honeydew they excrete, much like a farmer milks a cows.