Red wood ant

The red wood ant (Formica rufa) is a member of the Hymenoptera order and the Formicidae family. While these ants are recognized as beneficial forest insects, in agricultural and horticultural settings, they act as significant pests due to their agricultural relationship with sap-sucking insects.

These ants cultivate and protect colonies of aphids, scale insects, and mealybugs to harvest honeydew. By shielding these pests from natural predators such as ladybugs and hoverflies, the ants ensure the survival and proliferation of aphid populations on fruit trees and ornamental crops.

The biology of Formica rufa revolves around large, complex colonies that can contain multiple queens. They establish durable trails from their mounds to various host plants. During the spring and summer months, their activity on trees is at its peak, significantly accelerating the spread of aphids throughout the garden.

The damage caused is primarily indirect but highly detrimental. Heavy aphid infestation, maintained by the ants, leads to severe plant stress, stunted shoot growth, leaf curling, and fruit drop. Furthermore, the secretion of honeydew promotes the growth of sooty mold, which blocks sunlight and hinders photosynthesis.

Effective control measures require a multifaceted approach. Installing sticky bands on tree trunks is a physical barrier that prevents ants from accessing the aphid colonies. Additionally, gardeners should manage aphid populations using insecticidal soap or specialized systemic pesticides, while removing weeds that serve as auxiliary breeding grounds for the pests.