Yellow citronella ant

Systematic position: The species belongs to the order Hymenoptera, family Formicidae. Lasius interjectus, commonly known as a type of citronella ant due to the lemon-like smell released when crushed, is a subterranean species that primarily operates beneath the soil surface.

Host plants and damage: These ants are particularly harmful to garden plants, ornamental shrubs, and turfgrass. While they do not consume plant material directly, their nesting activity disrupts the soil structure around roots, creating air pockets and exposing delicate root systems to drought and soil-borne pathogens.

Biology and lifecycle: The lifecycle follows a complete metamorphosis: egg, larva, pupa, and adult. The colony structure typically includes multiple queens, making them highly resilient and difficult to eradicate. They spend most of their life cycle underground, which makes detection of an infestation challenging until plant symptoms appear.

Damage profile: The major economic impact stems from their mutualistic relationship with root-feeding aphids and mealybugs. The ants actively transport these pests to the plant roots, protect them from predators, and nurture them, leading to severe infestations that deprive plants of essential nutrients and lead to stunted growth or death.

Effective management strategies for Lasius interjectus include:

• Targeted application of granular insecticides in suspected nesting areas.
• Frequent soil cultivation to disrupt nest galleries and discourage establishment.
• Use of systemic insecticides to control the aphid populations the ants are protecting.
• Applying botanical repellents like essential oils around the base of affected plants.
• Monitoring turf and garden beds for signs of "heaving" or excessive soil disturbance.