If you have ants in your garden, you might wonder if it is wise to get rid of them or let them be. These tiny critters aren’t always dangerous since they offer several benefits to the ecosystem. However, a severe ant infestation in your garden can be a real headache, in which case a natural method is the best way to control them.
Here are 11 natural ways to get rid of ants in a garden:
- Identify the ant species in your garden.
- Use boric acid bait to kill the ants.
- Apply citrus oil to repel the ants.
- Use peppermint oil to repel the ants.
- Use spinosad to kill invasive ants.
- Attract ant predators.
- Keep aphids away from your garden.
- Use diatomaceous earth (DE).
- Pour boiling water into the ant nests.
- Grow ant repelling plants.
- Maintain a healthy garden.
This article explores the above ant management strategies in detail. So, read on to learn how to control your garden’s ant population.
1. Identify the Ant Species in Your Garden
A vast array of ant species exist globally – there are about 12,000 of them. If you’ve seen some ants in your garden, it can be daunting trying to figure out how to control them if you don’t know what species they are. Ants can vary in size and color, but that’s not all.
Ant species also differ in:
- Behavior, such as biting, stinging, destroying structures or plants
- Feeding habits and preferences
- Habitat (nesting) preferences
This means you can’t apply one control method to eliminate all ant species.
It would, therefore, help if you could identify the ant species that has invaded your garden before settling on the best management strategy.
Many of us know what a typical ant looks like. It is wingless, has a tiny, thin body, and a pair of antennae. However, did you know that some ants are winged? Most people mistake these ants for winged termites (or swarmers).
To get started, let’s look at the physical differences between ants and termites:
|Constricted, with one or two bumps (nodes)
|Unconstricted, and rectangular-shaped
|Wing size (if applicable)
|Hind wings are shorter than fore wings
|Hind and fore wings are generally the same size
|Elbowed (bent) antennae in worker and winged female ants
|Unbent antennae in all termites
Note: Winged ants and termites leave their nests during warm weather to mate, and lose their wings after flight.
Now that you know how to distinguish an ant from a termite, it’s a good idea to be able to distinguish between the different ant species. Ant images from books or the internet can assist in identification, but it’s not always easy to match a picture with the real thing, and you might need to consult an expert.
It is essential to know what different ant species look like, how they feed, and where they build their nests. You should also know what species are prevalent in your region.
So, let’s explore the various ant species that are found in the United States:
Ant Species in the United States
About 1,000 ant species exist in the US, with some states (such as California) having over 270 species. Some are a nuisance and can be irritating, primarily when they infest your home. Others, however, are beneficial to gardens, lawns, and the ecosystem.
Here are several benefits of having ants in your garden (or on your lawn):
- They assist in pollination since they transfer pollen (unknowingly) when moving from one flower to another.
- Ants feed on some destructive garden pests and their eggs, including aphids and mites.
- They aerate the soil by creating tunnels.
- Ants help enrich the soil by enabling plant and animal debris decomposition by fertilizing it with their feces.
Nonetheless, ants can pose a challenge to gardeners and homeowners due to the following reasons:
- They shield or enable plant pests, such as aphids and mealybugs. Ants benefit from the honeydew fluid that sap-feeding bugs produce after invading plant leaves.
- Sometimes, ants feed on plants during the dry season.
- Some ants, such as fire ants, sting and bite humans.
- When ants build nests near plants, especially young ones, they can destroy them.
- Large anthills hamper lawn mowing activities.
- Some ant species destroy wooden structures.
Here are the most common ant species in the United States:
Carpenter ants (Camponotus Spp) have the following characteristics:
- Appearance: Red, or red+black, large workers (¼ – ½ inch long/0.63 -1.27cm) and queens (¾ inch long)
- Preferred foods: Sweets, other insects, proteins
- Nesting sites: Decaying wood, hollow spaces, damp areas, and under roofs
- Damage/Benefit: Destroy wooden structures
Despite their name, Argentine ants (Linepithema humile) are common in the USA, and have the following main characteristics:
- Appearance: Dull brown ⅛ inch (0.32cm) long
- Preferred foods: Sweets, proteins (sometimes)
- Nesting sites: Outdoors in shallow mounds
- Damage/Benefit: Nuisance pest, affects biodiversity
Velvety Tree Ant
Velvety tree ants (Liometopum occidentale) are distinguishable as follows:
- Appearance: Brownish-black head, yellowish-red thorax, and velvety abdomen; ⅛ -¼ inch long
- Preferred foods: Sweets and insects
- Nesting sites: Dead wood
- Damage/Benefit: Biting and nuisance pest, destroys structures
Odorous House Ant
Below is how you can identify odorous house ants (Tapinoma sessile):
- Appearance: Brown to dark brown with uneven thorax; 1/10 inch (0.25cm) long
- Preferred foods: Sugary food, live insects, meats
- Nesting sites: Soils under plastic mulch, boards, or patio blocks, indoors in moist areas
- Damage/Benefit: Nuisance pest
Field ants (Formica spp.) have the following features:
- Appearance: Red, brown, or black, uneven thorax, distinct simple eyes; ⅛ to ¼ inch long
- Preferred foods: Sweet food, honeydew, insects (live and dead)
- Nesting sites: Large soil mounds in exposed areas, under objects (wood, patio blocks)
- Damage/Benefit: Serious nuisance pests due to large mounds
Red Imported Fire Ant
Here is how red imported ants (Solenopsis invicta) typically look and behave:
- Appearance: Reddish with dark-brown abdomen; 1/16 to ⅕ inch long
- Preferred foods: Sweets and proteins
- Nesting sites: Soil or lawn mounds with several openings, sometimes indoors in behind wall voids
- Damage/Benefit: Stinging/biting, serious nuisance pest
Pharaoh ants (Monomorium pharaonis) can be identified as follows:
- Appearance: Light yellow to red, small ants (1/16 inch long), spineless thorax, antennae has 12 segments
- Preferred foods: Sweets, fats, proteins (dead insects), soaps, toothpaste
- Nesting sites: Indoors in warm, moist areas such as cracks, crevices, and small spaces
- Damage/Benefit: Nuisance pest
Acrobat ants (Crematogaster spp.) have the following features:
- Appearance: Yellow-brown to black, with two spines on thorax, ⅛ inch long
- Preferred foods: Sweets, meats, insects
- Nesting sites: Soil (under trees), dead/rotten wood
- Damage/Benefit: Nuisance pest
Below is some information on pavement ants (Tetramorium caespitum):
- Appearance: Reddish-brown-to black, two spines on thorax, grooves on the head and thorax; ⅛ inch long
- Preferred foods: Sugary and fatty food, meat, pet food, bread, nuts, insects
- Nesting sites: Driveways, sidings, under logs and concrete slabs
- Damage/Benefit: Nuisance pest
Here are main characteristics of thief ants (Solenopsis molesta):
- Appearance: Yellow to light-brown; 1/32 inch long
- Preferred foods: Fatty/greasy foods, ant larvae from other ant species
- Nesting sites: Soil, under rocks, in decaying wood, indoors in wallboards or baseboards
- Damage/Benefit: Nuisance pest
2. Use Boric Acid Bait To Kill the Ants
After identifying what ant species have invaded your garden, one of the most effective ways of controlling them is using boric acid (borax).
Boric acid is among the most widely used compounds in pest control and management. It is a hydrated salt that contains sodium, boron, and oxygen. This widely-used mineral is a common ingredient in numerous products, including pesticides, household cleaning agents, and cosmetics.
Borax is effective in getting rid of various ant species, especially those that love sweet food, and building nesting sites underground, such as:
- Fire ants
- Velvety tree ants
- Carpenter ants
- Field ants
- Argentine ants
- Pharaoh ants
- Acrobat ants
Boric acid is ideal for controlling ants, as it is toxic to ants and effectively kills them. The mineral disturbs their stomachs, hampers their nervous systems, and damages their exoskeleton.
Since borax is odorless and tasteless to the ants, mixing it with sugar or honey to make bait is the best way to use it.
Ants are eusocial creatures, as they live in colonies, and the members have specific roles. The worker ant’s job is searching for food, and if you lace borax with sugar, these ants will carry the food back to their nests to feed the larvae, drones, and queens.
This means that you don’t have to look for their nesting sites (which is a good thing as they can be several feet under the soil).
Borax is relatively safe for humans. However, you should keep it away from kids and pets since severe exposure to boric acid can cause:
- Eye damage
- Nausea and vomiting
- Bleeding from the nose
It’s important to note that if you have identified an ant nesting site in your garden, use borax sparingly. Even though the mineral is vital for plant growth, using it excessively can lead to toxicity. In such cases, the plants might experience:
- Splitting leaves or bark
- Necrosis (cell death) at the root tips
3. Apply Citrus Oil To Repel the Ants
Another natural way of getting rid of ants in your garden is by applying citrus oil. Citrus oil is an essential oil comprising bergamot and monoterpene hydrocarbons, such as D-limonene. The D-limonene is toxic to ants, will kill them on contact, and will also destroy the chemical trail they leave behind for other ants.
If you want to use citrus oil to eliminate ants in your garden, apply it to the individual ant mounds. Applying it throughout your garden, and anywhere you think you may have an infestation can inadvertently kill beneficial ants.
For instance, applying citrus oil to mounds belonging to invasive and imported fire ants allows you to mitigate the risk to native ants, which naturally help reduce the population of foreign ants.
A study compared the effectiveness of orange citrus oil and hemp oil in repelling fire ants (Solenopsis geminate). The findings showed that orange citrus oil was more effective and consistent in repelling the ants.
Another experiment on the efficacy of citrus oil (in an orange oil and liquid dishwashing soap mixture) in treating fire ant mounds showed that fewer ants were active on consecutive days, indicating that citrus oil deterred the insects.
Applying citrus oil is also practical in states (such as Oklahoma, Texas or Alabama) where these ant species are prevalent, and a nuisance to residents.
Experiments on the use of citrus oils in ant control in the three states involved comparing the efficacy of commercial and homemade citrus products and diazinon formulations. Preparing the homemade citrus oil concoction entailed mixing water with equal parts of:
- Raw citrus peel extract
- Cattlemen’s molasses
- Compost tea
The commercial citrus oil product comprised Erath Earth Orange Oil extracts.
The results revealed that homemade and commercial citrus oil extracts were 80% (or more) effective in controlling imported fire ants when used as a mound drench. However, preparing the home-based formulation is challenging since you might have the wrong concentration.
Buying a natural commercial citrus oil product is, therefore, preferable since it has the correct concentration. Moreover, the individual mound drench treatment is only practical when experiencing small-scale ant infestation.
Another laboratory study revealed that Mandarin orange (Citrus reticulata) is also an effective insect repellent. The fruit contains about 95% limonene, which is toxic to ants, and the terpene affects the insects’ respiratory system.
Mandarin orange is effective at repelling ants and mosquitoes. However, current studies have only focused on using it in controlling ants in a laboratory, and more research is needed for its efficacy in a real-life setting.
4. Use Peppermint Oil To Repel the Ants
Peppermint oil is another essential oil that you can use to keep ants away from your garden. The oil is derived from the famous peppermint plant, a natural hybrid of spearmint and watermint.
Peppermint oil comprises three ingredients, namely menthol, menthone, and pulegone. Menthol is the major component of peppermint and aids in controlling ants and other insects invading gardens and homes in two ways:
- It repels them due to its strong scent.
- It kills the bugs since menthol has biocidal properties.
Several studies have investigated the efficacy of peppermint oil in repelling and treating pests. An experiment on the effect of peppermint oil on two ant species, the Argentine ant and the red imported fire ant, revealed that the oil was effective in repelling the ants at 1% concentration.
Another study compared the repellency capability of five essential oils to the Argentine ant, including:
- Peppermint oil
- Spearmint oil
- Cinnamon oil
- Clove oil
- Wintergreen oil
The Argentine ant (an invasive species) has become a concern to most American residents since it has outperformed the native ant species in its multiplication capabilities. It forms supercolonies, living in shared ant colonies and has reduced intraspecific aggressiveness.
The experiment on the efficacy of five essential oils in repelling the Argentine ant acknowledged that the oils’ effectiveness in repelling insects diminishes after a few days.
The reduced repellency capability can be due to the following:
- Evaporation of the essential oils
- Losing the strong scent due to aging of the essential oil
Relying on essential oil treatments as long-term insect (or pest) deterrents is, therefore, challenging.
5. Use Spinosad To Kill Invasive Ants
Produced through bacterial fermentation, spinosad is an organic insecticide that has become a sensation among gardeners.
The US Environmental Protection Agency (EPA) approved spinosad as a pesticide in 1997, and the USDA National Organic Program approved it as a natural insect killer in 2003.
It’s effective against invasive ant species, such as imported fire ants, since it is toxic and damages the ants’ nervous system.
After ingesting it, the ants become paralyzed and die after a few days. You can use it as bait on targeted ant populations or spray it around the nesting sites.
Spinosad is safe since it’s not toxic to the soil and plants. It breaks down quickly when you expose it to sunlight, and plants don’t absorb it readily. It also doesn’t leach into the ground quickly, and is safe for use as a long-term insect killer.
Many gardeners don’t know about it since it’s available as a commercial product under different names, including:
- Ferti-lomeR Borer
- Monterey Garden Insect SprayR
- Ferti-lomeR Borer, Bagworm, Leafminer & Tent Caterpillar Spray
- Bulls-EyeTM Bioinsecticide
6. Attract Ant Predators to Your Garden
Unlike other insects, ants have few predators. Hence, after identifying the ant species that have invaded your garden, it would help if you determined if they have natural predators. Some ant species, such as Argentine ants, sometimes lack natural enemies.
Other species, like imported fire ants, have natural predators, namely phorid flies. However, these flies weren’t originally native to the US.
Scientists introduced phorid flies in 2004, which are fire ants’ parasitic enemies from South America. These hump-back flies resemble whiteflies, are common in mausoleums or places with human corpses, and commonly referred to as coffin flies.
Although some phorid fly species are nuisance pests, others have proven to be effective biocontrol agents. For instance, about 24 species of phorid flies attack fire ants and interfere with their foraging behaviors.
The larvae of these phorid fly species serve as parasitoids that grow in the heads of the fire ants. The flies destroy the ants upon reaching the pupa stage, and if the phorid fly is female, it mates upon reaching adulthood, and the cycle continues.
Aside from phorid flies, there are also other animals that enjoy eating these ants:
- Some spider species, such as the jumping spider
- Some birds like sparrows, wrens
- Antlions (doodlebugs)
- Horned lizards
- House geckos
These ant-eating organisms feed on ants naturally in the ecosystem, and introducing them to your garden could help.
An easy way to attract ant-eating creatures to your garden is to put up bird feeders and fill them with seeds that sparrows and wrens like.
7. Keep Aphids Away From Your Garden
Most ant species love feeding on sweet food items, including:
Some ant species (like Velvety and Field ants) love feeding on honeydew. This is a sweet fluid that sap-sucking insects, such as aphids and mealybugs, secrete after feeding on plant species.
Honeydew-loving ants are more likely to invade gardens infested by these sap-feeding bugs. The two types of insects have a mutual relationship, where the ants protect the sap-feeding pests from predators and parasitoids. In return, they benefit from the sugary extract that these sucking bugs produce after feasting on the plant tissues.
So, if your garden is experiencing an attack by sap-sucking insects (mainly aphids), it would help if you got rid of them to keep the opportunistic ants at bay.
Here are some natural ways to control aphids in your garden:
- Introduce aphid predators to your garden, including parasitic wasps, lacewing larvae, ladybird beetles, syrphid fly larvae, and soldier beetles.
- Spray aphid-infested plants using an insecticidal soap solution.
- Remove weeds that host aphids, such as mustards and sowthistle.
- Spray the aphids with water to dislodge them from plants.
- Use yellow sticky tape to trap aphids.
- Plant crops that attract natural aphid predators, such as cowpeas, sweet fennel, crimson clover, and spearmint.
- Avoid planting aphid-attracting crops like birches.
- Ensure that your plants are healthy by supplying adequate nutrients and other growing requirements.
Getting rid of aphids will also reduce (and gradually wipe out) the populations of honeydew-loving ant species, including:
- Velvety ant (Liometopum Occidentale)
- Field ant (Formica spp.)
- Odorous house ant (Tapinoma sessile)
- Larger yellow ant (Lasius interjectus)
- False (small) honey ant (Prenolepis imparis)
- Cornfield ant (Lasius americanus)
- Carpenter ant (Camponotus spp.)
8. Use Diatomaceous Earth (DE)
Diatomaceous earth (DE) comprises the fossilized remains of aquatic organisms called diatoms (algae) – hence the name. These remains are made of silica, a common mineral in many parts of the world.
DE is a natural substance, and an active ingredient in most pesticides since it kills insects and other pests, such as:
However, it doesn’t kill the bugs after they ingest it. Instead, it is abrasive and destroys the insects’ exoskeleton. It does this by penetrating the exoskeleton, causing the insect to dehydrate, and then die.
Using DE is an effective way to eliminate ants in a garden. It is also natural, making it safe for use if you have pets.
In addition, it has a simple application process, which involves:
- Monitoring the ants’ trail to locate their nesting site
- Sprinkling the DE at (and around) the entrance to the nesting site
- Mixing it with water (4 tablespoons per 1 gallon of water) to form a suspension and pouring it into ant mounds
It’s important to note that although DE is safe to use, it’s best to wear gloves and a face mask when using it so that you don’t expose yourself to the powder. Inhaling or coming into contact with DE may cause eye or skin irritation, coughing, and shortness of breath.
Diatomaceous earth only works optimally when dry, and it won’t be effective when it is rainy or humid.
Though it’s an effective ant killer it may not wipe out an ant colony entirely. It might kill a few ants and force them to abandon one nesting site. However, the ants will multiply quickly if the DE doesn’t get to the queen.
It’s a good idea to study its effect on the ants and consult a professional pest control expert if the ant population resurges shortly afterward.
9. Pour Boiling Water Into the Ant Nests
A physical treatment approach would be suitable if you’re experiencing a small-scale ant infestation. Using scalding water at about 190°F – 212°F (88°C – 100°C) is an effective method.
Pouring hot water into individual ant mounds, especially on sunny, cool mornings, can kill numerous ants since most of them will be near the opening. Using around one or two gallons of boiling water will eliminate about 60% of the ant population in the mound.
The scalding water can get to the queen and eliminate the whole colony if the nesting site is shallow.
However, if the mound is deep (about 6 feet or 2 m), the initial appearance of the boiling water will force the worker ants to move the queen deeper into the mound. You might, therefore, be unable to wipe out the entire colony.
This may necessitate repeating the process until you have successfully eliminated the entire colony.
Take care when using this method as you may accidentally burn yourself or harm any surrounding plants by scalding them.
10. Grow Ant Repelling Plants
Most ant species use scents to make chemical trails when searching for food or finding their way back to the nesting sites. This means that they have a strong sense of smell. However, like other organisms, ants won’t always like all odors.
There are some smells that ants find unpleasant or irritating, and this could be a blessing in disguise since you can use them to repel invasive ants from your garden. This natural ant control method will not harm your organic garden.
A practical way to do this would be to grow ant-repelling plants in your garden, along the sidewalks, or on your fence. The plants will repel the pests and keep them away from your property.
Here are some ant-repelling plants that you can grow in your garden:
You can also make ant-repellent sprays by using the leaves or flowers of some of these plants. For instance, you can mix basil with witch hazel and make a suspension by adding water to the mixture to repel ants.
Also, some plants such as chrysanthemums, lavender, and marigolds are visually appealing. So, you’ll be adding esthetic value to your garden while keeping nuisance ant species at bay.
Bear in mind that planting certain plants like eucalyptus can positively and negatively affect your land. Various studies have focused on the ecological impact of this fast-growing tree and revealed a few disadvantages of growing eucalyptus.
- It dries out shallow water sources due to its intensive water requirements.
- Eucalyptus can minimize biodiversity since its leaves have allelopathic properties – that is, no ground vegetation can survive near the tree.
- It lowers the soil’s nutrient capacity since it is fast-growing and consumes a lot of nutrients.
11. Maintain a Healthy Garden
Most ant species target gardens with favorable conditions, including the availability of food and nesting sites. Therefore, if your backyard (or garden) is full of plant debris, spilled food remains, or uncovered garbage cans, it will attract these insects.
Some ants also invade gardens and feed on plants during hot, sunny months. Therefore, taking care of your garden is essential to ensure it is healthy and minimize ant infestation.
You can achieve this by:
- Watering your plants properly, especially when it is hot
- Removing plant debris
- Excavating ant mounds, especially near plants or on the lawn
- Keeping wooden piles or logs away from your garden
You can also use baby powder (talcum) to repel ants when evacuating the ant mounds since it deters them. Some studies have shown that talcum powder alters the behavior of most ant species and can even kill them. You can also use it as a physical barrier after mixing it with ethanol.