Garden ants

The genus Lasius belongs to the family Formicidae, order Hymenoptera. Within this genus, the black garden ant (Lasius niger) is widely recognized as a significant pest in horticulture and agriculture. These ants are social insects living in complex subterranean colonies, often establishing their nests near the base of garden plants, which directly impacts their health.

These insects affect a vast range of crops, including fruit trees, berry bushes, and vegetables. While they do not consume the plants as a primary food source, their presence is consistently linked to severe pest infestations. They are problematic in greenhouses, orchards, and open fields alike, often undermining the soil structure and stability of young plant root systems.

The biology of Lasius is defined by a mutualistic relationship with aphids. Ants farm these sap-sucking insects to harvest honeydew, a sugary excretion produced by aphids. To maximize their yield, ants actively transport aphids to succulent young shoots, protect them from natural predators such as ladybirds, and shelter them during adverse weather or winter months.

The damage caused by these ants is primarily indirect but devastating. Through the uncontrolled spreading of aphids, they cause nutrient depletion, foliage distortion, and reduced photosynthetic capacity in crops. Furthermore, the honeydew buildup serves as a substrate for sooty mold, which blocks light and impairs gas exchange in the leaves, weakening the overall plant.

Effective management strategies include the following:

• Installation of sticky barriers on tree trunks to block access to the canopy.
• Targeted application of bait stations containing slow-acting insecticides.
• Regular soil cultivation around the root zones to disrupt nest building.
• Implementation of biological control methods to suppress aphid populations.
• Use of aromatic herbs like mint or thyme as natural deterrents in planting zones.