Horticulture Magazine

How To Get Rid Of An Ants’ Nest In Your Garden

ants marching to their nest carrying leaves

It is not exactly unusual to have ants, or even an ants’ nest, in your yard.

In fact, ants perform multiple beneficial functions in the garden.

That said, there are some legitimate reasons to eradicate an ants’ nest, particularly if you have a problem with aphids or similar pests.

We lay out half-a-dozen methods, from plain old water to highly-technical nematode release.

Are Ants In The Garden A Problem?

an ants nest mound underneath a fallen tree trunk

So you have an ants’ nest in your garden.

Before you go ballistic and take out the heavy artillery, let’s take a minute or two to evaluate whether the ants are an actual problem and need to be taken care of, and, if so, choose a solution that fits the scale of the problem and will do no or minimum collateral damage. 

Ants in the yard are, well, normal. That doesn’t mean you have to have them in your garden if you don’t want to, it’s just to get across that there’s nothing particularly unusual about having ants in your garden.

ant hills in a garden lawn

You may be concerned because you know about an ants’ nest in your garden.

But many, many homeowners have ants’ nests in their respective gardens – but they don’t even know about the problem and so the ‘problem’ is not a problem.

So where an ants’ nest is concerned, perhaps ignorance is bliss.

If you know you have an ants’ nest in your garden, we’d recommend you only get rid of it if you also know that the ants are damaging your garden.

a newly built ant colony

Ants – A Balanced View

The purpose of this article is not to elaborate upon the benefits that ants can and do bring in the garden.

However, so that you can make a fully informed decision as to that ants’ nest, before we proceed to outline the ways to get rid of it, a concise outline as to the beneficial effects of these tiny insects.

yellow meadow ants

Ants, as such and under normal circumstances, are not garden pests. For the most part they are teeny-weeny ‘garden hands’.

To begin with, they are natural-born tillers of the soil.

Their incessant subterranean activity results in particulate matter from the surface being pulled underneath, deep down, and vice versa, improving the fertility of the soil.

Also, their tunnelling into and through the soil aerates it which assists in the decomposition of organic matter – dry leaves and dead earthworms alike.

magnified view of flower buds with two red carpenter ants harvesting nectar

Talk about dead earthworms, though ants are scavengers in the main, many UK species are also predators.

Many, if not most, species of ants actually control or reduce the population of garden pests because they prey on their larvae and eggs.

Some also attack and prey on the pests themselves.

Ants are territorial insects so as long as your garden has one ant colony you won’t be getting another one unless an invading troop attacks and defeats the resident ants.

On the other hand, if you destroy or ‘evict’ your garden’s resident ants, then sooner or later advance scouts or a roaming ant colony will come upon your yard, see it as virgin territory ripe for occupation, and lay down stakes!

two ants carrying a flower bud

Also keep in mind that ants play a part in a healthy garden ecosystem.

While they prey on various small garden pests, they themselves are themselves preyed upon by small birds and lizards.

Getting rid of an entire ant colony can throw that healthy garden ecosystem out of whack.

Believe it or not, there are yet more reasons to tolerate an ants’ nest in the yard but, like we said, this article is not about the positives of ants in the garden! 

illustrated view of ants tunnelling underground
Ants’ Sub-soil Activity is in General Beneficial for the Garden

When To Get Rid Of An Ants’ Nest

So why, under what circumstances, would it be the right decision to get rid of an ants’ nest?

First – are the ants ruining your landscaping and depositing piles of soil on the lawn? Is the ants’ nest tucked away by the fence or is it an eyesore? Is it getting bigger and bigger?

ants nest hole in a garden lawn

If the answers are ‘Yes,’ the affirmatives answer the bigger question too.

Second – if the ants’ nest is near shrubs and plants that have delicate roots or those that are wilting without any discernible reason, then the ants’ nest may have to go.

Though subsoil ant activity is a good thing in general, when it is below or beside delicate roots, it can disturb them and affect their uptake of soil nutrients.

ants nest in the middle of a grass lawn
Definitely Not What you Want to see on Your Lawn!

Third – does your garden have an aphid problem that you can’t get under control? Or a mealybug or whitefly problem? If yes, then you must get rid of the ants’ nest.

That’s because the ants, albeit indirectly, are a threat to your garden. Ants and aphids go together; they have a symbiotic relationship.

Just as supply ships victual the Navy while being protected by destroyers, so do aphids provide food to ants, and in turn are protected by them.

ants and aphids on a green stem
Ants and Aphids have a Symbiotic Relationship

The same goes for mealybugs and whiteflies. 

Concisely, aphids, mealybugs and whiteflies as honeydew-producing garden pests are of value to ants because these pests provide sustenance to ants: ants gather the honeydew that these pests secrete and take it to their nest, mainly for the queen but also for the colony.

This means that if you release ladybirds or lacewings to destroy aphids, mealybugs or whiteflies, your efforts may come to naught because the ants will protect the garden pests (as they are well known to do), and may well kill the ladybirds and lacewings.

aphids and black ants working together on the underside of a leaf

If you make the decision to destroy an ants’ nest, be aware that its actual size underground will be far larger, probably some multiple, of the size you may estimate by what is visible on the surface.

Facts To Bear In Mind 

Over 30 ant species inhabit the United Kingdom.

The most commonly-found ones are black ants (Lasius niger), yellow meadow ants (Lasius flavus), red ants (Myrmica rubra) and wood ants (Formica rufa).

red ants on green garden leaves
Red Ants are a Common Type of Ant in British Gardens

These different ant species have different levels of resistance and susceptibility to the ant-control methods outlined underneath.

For instance, a black ants’ nest is very likely to be wiped out by bait stations but the same can’t be said for those of wood ants.

Likewise, a red ants’ nest is equally likely to be very adversely impacted by the sugar-borax method but not a black ants’ nest.

On the other hand, neither of these methods will make much of a dent in a yellow meadow ants’ nest.

Therefore, if one method does not work, do not be discouraged but try another one.

small black ants outside their nest
Black Ants on One of Their Foraging Pathways

Avoid trying to mix and match methods as one method may attenuate the efficacy of the other.

Choose one method and stick with it until it succeeds or fails.

Most of the well-known commercial insecticides and applications for reducing the presence of ants are formulated for use in dwellings and other buildings.

These are not meant for use in the garden and may well cause damage to plant life.

Also, though these applications will certainly kill ants in exposed locations then (except for ant bait stations) they will not be of any effect in eliminating an ants’ nest.

1) Boiling Water

an ants nest with obvious entry holes
Sometimes an Ants’ Nest’s Entry / Exit Holes are Obvious and Easy to Spot

Boiling water is a well-known ant-killer but, for obvious reasons, this is not a solution for the lawn or close to plant life.

If the ants’ nest is a metre or so away from the lawn or from the estimated extremity of the root system of the nearest plant, pour boiling water – bucketfuls – on the nest and into all the holes you can see; if not, then douse the ants’ nest with bucketfuls of cold water every day or two (unless succulents or such are nearby!).

You could also run water – lots of it – through the hosepipe and jet it into all the entry/exit holes that you can spot.

If there is no plant life at the spot, put pieces of soap or gobs of dishwashing liquid at the entry/exit holes so that the water that gushes into the nest is soapy water.

Either way, you should soon see ants scurrying hither and thither. Continue this ‘water torture’ for several days on end.

Ants dislike damp conditions, let alone wet, soapy ones, and will soon decide to shift to a more congenial neighbourhood.

2) White Vinegar

a pressure washer spraying a patio

White Vinegar is another well-known ant-killer which – unlike boiling water – will not harm plant life.

It is the mild acid in white vinegar that is the knockout agent. How, though, to deliver the vinegar where it counts – in the nest?

Fill a jet washer or jet spray machine with white vinegar and shoot it into the ants’ nest’s entry/exit holes.

If you cannot spot them, then spray it all around the ants’ nest, surrounding and soaking it with white vinegar.

You will have to do this several times but the net result will be the elimination of nearly the whole colony with the survivors hightailing it for less inhospitable nesting grounds.

3) Diatomaceous Earth

gardener sprinkling white Diatomaceous earth using a trowel

Sprinkle food-grade diatomaceous earth all around the ants’ nest, especially where you spot the entry/exit holes. Try to get it in the holes.

Diatomaceous earth will kill the ants, but there’s a catch: it will also kill other insects and may also kill small garden life such as lizards and amphibians.

That is because the microscopic razor-sharp edges of diatomaceous earth abrade insect exoskeletons and also dehydrate insects and small animal life.

Damp and wet conditions greatly degrade the potency of diatomaceous earth so be sure to use it when the earth and the weather are both dry.

This ant control technique is in the main an effective one for all types of ants and though it will not eliminate an ants’ nest it will at least keep reducing the ant population.

4) Boric Acid & Sugar

ants crowded round a boric acid trap

This is the original ‘bait station’ technique that has been used by farmers and country gardeners for generations.

Do not use this method, especially, in conjunction with any other.

Make a mixture of sugar (preferably icing sugar) and boric acid powder in a ratio of 8 parts sugar to 1 part boric acid.

Mix this in bottled water so as to form a gooey liquid with the consistency of treacle or honey.

Do not use tap water as impurities in it could put off the ants from consuming the toxic bait or the minerals or ions in tap water could react with the boric acid and neutralise its potency.

Drop and spread this thick gooey concoction on and around the ants’ nest, particularly at the holes. Keep doing so every couple of days.

Worker ants will take this toxic mix into the nest for the queen and the rest of the colony.

The ants will consume it and gradually die of poisoning.

5) Nematode Steinernema feltiae

Parasitic entomopathogenic nematodes under a microscope

Steinernema feltiae are microscopic organisms that act as a slow poison – actually a disease – on an ant colony.

These nematodes enter the insects’ body cavities and then release bacteria, which destroy tissue and poison the ants.

The variables are that there are a few different brands of this nematode and several different species of ants.

One brand may deliver excellent results with one species while failing with another species.

These nematode formulations have to be used within a week or two of delivery, have to be mixed very precisely with water, and must not be applied in sunlight or under extreme temperatures.

Also, they are most effective between April and September.

BioLogic Scanmask is a product that combines Steinernema feltiae with diatomaceous earth.

One plus point of this method is that these nematodes act against most pests that are destructive to plant life but are harmless to beneficial predators as well as to plant life.

6) Ant Bait Stations

a bait station in a garden
A Bait Station out in the Garden

Ant bait stations are so constructed that ants, attracted to the enticing bait inside the plastic structure, can get in and out while other soil-dwelling insects are either not interested or cannot enter the precisely-fabricated station.

Worker ants collect the toxic bait, usually in gel form, and take it back to the nest for the queen and the rest of the colony.

As the appetising bait contains some or another potent poison, the ants start to die.

The few ants that remain cannot sustain the colony, which collapses. Bait stations can be placed by the entry/exit holes of the nest or along foraging pathways.

Ant Stop! and Maxforce LN are two very good choices.

The former contains fipronil as the active ingredient and the latter contains imidacloprid.

Goodbye Garden Ants!

closeup of a swarm of busy black ants on a stone structure

Eliminating an ants’ nest is not an exact science (and it is certainly not an art).

It is a trial-and-error process.

If you have decided to get rid of an ants’ nest, the important thing is to approach it as a difficult project that will require sustained work.

As a last resort, you can call in professional exterminators but do not get discouraged too quickly, and be persistent.

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