Understanding ant trails in the garden: Ecological background

Key points at a glance

• Ant trails are highly organised supply routes that serve primarily for efficient foraging.
• Orientation is achieved via pheromones (chemical scent signals) which guide workers to the food source.
• Observed cooperation with aphids is a natural process, not a reason for direct control measures.
• Ants make a decisive contribution to soil biodiversity through soil aeration and seed dispersal.

Why ants connect the garden

If you notice an increase in ant trails in your garden during July, this is an indicator of an active, growing ant colony. The insects do not act at random; every visible route is an energy-optimised path between the nest and a productive resource. This route formation is a biological necessity, as the colony's energy requirements reach their seasonal peak during the rearing of larvae.

Communication between workers, for example, the black garden ant (Lasius niger), takes place primarily via pheromones. These are chemical messengers that the ants release on the ground. The more frequently a route is used, the more intense the scent trail becomes, which leads further workers to the same source. This behaviour should be understood as an efficient collection system that allows the animals to precisely target even distant food sources, such as aphid colonies or prey.

The symbiotic relationship: ants and aphids

Often, an ant trail leads directly to a plant colonised by aphids (Aphidoidea). The aphids feed on plant sap and excrete excess sugar as honeydew – a valuable energy source for the ants. The ants 'milk' the aphids by stroking them with their antennae to stimulate the release of this secretion.

Instructions for the nature garden

1. Observe the route of the trail without interfering. Identify the destination; these are usually aphid colonies on young shoots or the undersides of leaves.
2. Check whether the affected plants are suffering from the aphid infestation or if the plant is vital enough to compensate for the sap loss.
3. Avoid using chemical agents or contact poisons. These destroy the ecological balance and kill beneficial soil organisms that are essential for humus formation.
4. Encourage natural predators of aphids such as ladybirds (Coccinellidae) or hoverflies (Syrphidae). These will regulate the population without your intervention as soon as the food supply for their larvae has been established.
5. Use ant trails as an indicator of the ecological health of your garden. A garden with high ant activity usually testifies to a vibrant soil life and intact ecological connectivity.

Frequently asked questions

Do I need to control ant trails?

No. Ants are essential for soil quality and seed dispersal. Observe them as part of the natural balance instead of trying to eliminate them.

Why are ants interested in aphids?

Ants use the honeydew from aphids as an energy-rich food source and, in return, actively protect the aphids from their natural predators.