Repelling or eliminating ants from our vegetable garden, garden, or terrace is certainly not a simple task. These insects can indeed pose a serious problem for our crops and more. Anyone who tends to a vegetable garden or garden has inevitably faced the dilemma of how to repel ants from their plants. While these creatures may appear simple on the surface, these insects are among the most evolved life forms in our ecosystem, boasting the most complex and organized society in the animal world. Naturally, not all of their actions are negative; they have important functions within the ecosystem. This is why the best strategy we feel inclined to recommend is damage containment, avoiding the use of pesticides. In essence, it’s better to deter them rather than eliminate them.
In this article, we present a series of biological remedies, from deterrents to more impactful solutions. But first, let’s get to know this insect better.
Ants, scientifically known as Formicidae, belong to an extensive family of insects in the order Hymenoptera.
Experts hypothesize that ants appeared on Earth over 150 million years ago. They are therefore one of the oldest life forms still present on our planet.
There are thousands of ant species. Morphologically, they have a body divided into three distinct parts, called tagmata: the head, thorax, and abdomen. From these body parts, other appendages originate: legs, wings, and antennae. The presence of wings categorizes ants under the order Hymenoptera, a word of Greek origin meaning “membranous wings”.
Other insect species belonging to this order include bees and wasps. Unlike bees and wasps, ants have wings only on individuals destined for reproduction: males and queens. Sometimes wings are entirely absent or are shed during the insect’s lifetime. In some species, for instance, queens shed their wings after mating to use them as a food reserve.
Another physical characteristic of ants is their stinger, potent and active in more primitive species. In more evolved species, however, this feature has been lost and replaced by more efficient chemical weapons, such as formic acid. The presence of a stinger signifies the close link between ants and wasps, from which ants are believed to have originated.
Social Organization of Ants
To understand how to eliminate or, better yet, deter ants from your plants, it’s useful to grasp their social organization. By definition, ants are social beings, living and collaborating together for survival. Their ability to cooperate is unique; this virtue has allowed them to develop highly efficient methods for transporting food and defending the colony. Their social behavior is so advanced that they are termed eusocial insects.
The salient features of ant social organization are:
- Division of labor;
- Overlap of more than two generations in the nest;
- Cooperative care of offspring.
In the most evolved forms, colonies become superorganisms, as ants appear to act as a single entity.
Roles within the colony can be summarized as follows. Firstly, there’s the queen, mother of all ants in the anthill, solely responsible for laying eggs. Then there’s the “king”, or male, which serves only for mating, after which it dies.
From fertilized eggs, sterile ants emerge and are divided into three categories:
- Small workers responsible for caring for the queen and larvae;
- Large workers specialized in gathering food;
- Soldier ants, larger than the others with powerful mandibles, tasked with defending the anthill.
Before discussing methods to eliminate ants, it’s interesting to understand their communication system. This happens through the release of pheromones, which are essentially traces of odors. These odors are detected through their sensitive antennae and released to be followed by the worker ants. For example, when ants search for food in groups, the ant that finds food marks a trail on the way back to the anthill. This path is then followed by other ants, which, once they reach the food, return to the colony as a group, following the same route and reinforcing it with additional chemical signals. When the food source is depleted, they stop marking the path, and the scent gradually dissipates.
This communication system increases the species’ survival rates, even during significant environmental changes. For another example, if a path established for a food source is suddenly blocked by an obstacle, one of the ants abandons it to explore new routes. If successful, it leaves a new trail of pheromones, marking the shortest route for the return journey. Successful routes are followed by more ants, ensuring that the best path is always used for food retrieval.
Damage to Crops Caused by Ants
Given that ants are highly evolved and exceptional insects, let’s move on to the downsides. What damages can ants cause to our cultivated plants?
Firstly, ants are carriers of crop pests, especially aphids and scale insects. These insects are known to produce honeydew, a sweet and sticky liquid that soils crops. Ants are fond of this honeydew, which is rich in sugars. To keep a steady supply of honeydew, ants farm aphids or scale insects, forming a symbiotic relationship. During winter, they shelter these insects in the anthill. Come spring, they transport them to plants, causing damage to crops. If you notice an aphid infestation on your plants, you can be sure that ants are behind it.
Another direct harm that ants can cause is the erosion of plant root systems or parts thereof. If plants grow near an anthill, they’re likely to damage the roots, especially in the early stages of growth. This attack can sometimes be fatal to the plant and certainly impedes the root system’s growth.
Ants can also effectively steal seeds. With a broadcast seeding technique on a limited surface, significant damage can occur. As we observed earlier, ants are incredibly organized in collecting food, making it easy for them to take a substantial number of seeds in a short amount of time.
How to Eliminate Ants from Plants: Organic Remedies
Let’s now explore how to eliminate ants from your garden or yard. However, it’s important to note that completely eliminating them is almost impossible, as they are highly organized, capable of surviving even in the harshest conditions. The best approach is to seek a balanced coexistence. In our case, the goal is to protect what matters most to us—our plants.
Another important note: we strongly discourage the use of harmful toxic pesticides that poison the environment and don’t necessarily solve the problem. We always recommend relying on products allowed in organic farming.
Potassium Soap and Marseille Soap
We’ve already talked about using potassium soap and Marseille soap as natural pesticides. They are also effective for eliminating ants, especially potassium soap. You can find a specific plant formulation here.
Simply prepare a mixture of water and potassium soap and spray it directly on the ants or on the parts of the plant affected by them. The ants will die instantly, along with any aphids. Additionally, the water and soap will wash away the honeydew left on the plants. The limitation of this remedy is that it has a local action, working on contact. Therefore, it’s not guaranteed that ants won’t reappear in the same spot to cause damage. Furthermore, avoid spraying the solution on flowering parts of the plant; focus on trunks, stems, and leaves. In the photo, you can see the use of potassium soap against ants on a cannabis sativa plant. Based on our field experience, we’ve observed that ants are quite voracious with this plant, and the photo shows the significant damage they can cause to the stem.
Another rather effective remedy allowed in organic farming to eliminate ants is pyrethrum, particularly in powdered form. For more information, we recommend reading our article on pyrethrum and its limitations.
For ants, boric acid is a chemical element that induces toxicity. Therefore, it can be effectively used as a repellent or insecticide to deter or eliminate ants. For instance, you can sprinkle common borax (which contains boric acid) around the plant’s stem, and ants will avoid it for a while. Highly effective is the use of borax (sodium tetraborate), formerly known as Venetian borax. This important boron compound is commonly available. You can prepare a paste with borax, water, and sugar, applying it on pieces of cardboard to be placed strategically along ant trails. Attracted by the sugar, ants will carry this paste to the anthill. However, once ingested, they will die due to poisoning.
There are other readily available substances to deter or eliminate ants. For example, chalk, baking soda, powdered sulfur, and wood ash. In these cases, it’s recommended to create a sort of barrier, encircling the plant’s main stem to keep the insects away. Within the realm of household remedies, many suggest using cinnamon powder and macerated mint leaves as repellents.
- Texas A and M University, Texas FARMER Collection: “Managing imported fire ants in urban areas” – Discusses techniques for managing imported fire ants in urban settings using biological control methods.
- Interdisciplinary Centre for Mathematical and Computational Modelling, Biological Control: “Impact of Pheidole megacephala (F.)(Hymenoptera: Formicidae) on the control of Dysmicoccus brevipes (Cockerell)(Homoptera: Pseudococcidae)” – Explores the biological control of mealybugs using ants and their impact on the ecosystem.
- Taylor and Francis online, Southern Forests: a Journal of Forest Science: “Leaf-cutting ants in commercial forest plantations of Brazil: aspects and control methods” – Describes aspects of leaf-cutting ants in Brazilian commercial forests and various biological methods to control these insects.
- Wiley Online Library, Annals of Applied Biology: “Potential for ant control of tent building species of ants associated with Phytophthora palmivora pod rot of cocoa in Papua New Guinea” – Investigates the potential of using ants for biological control against tent-building species associated with cocoa pod rot.