Effective Ways of Killing Ants in Mulch

Have you encountered ants in mulch bag? 

Mulch is beneficial for your garden or lawn. It prevents weeds, improves water retention, and regulates the soil’s pH. The only significant downside is that mulch can harbor pests like ants. But do ants like mulch and what are the ways of killing ants in mulch?

Mulch stays undisturbed, making it an ideal hiding place for ants. The deeper the mulch layer, the better the ants’ shelter. Effective ways of eliminating ants in mulch include using boiling water, Boric acid, Diatomaceous earth, and bifenthrin pesticides.

Organic mulch containing sweet and sticky sap is more likely to attract ants than inorganic mulch, so being selective about the kind of mulch you use can help keep ants away.

You can kill ants using natural or chemical means. If all the methods we’ll list below fail, contact your local pest control agency.

Why Are Ants in My Mulch?

Ants are attracted to mulch because it provides humid conditions for them to thrive. Also, since ants love anything sweet and sticky, they will be more attracted to sweet and sticky mulch, like fresh grass clippings and sugarcane.

Mulch that does not attract ants includes cedar mulch with a strong fragrance that keeps ants away, tree bark mulch, or any other dry mulch like dead leaves.

Ants may also have been living in the soil but surface when you placed mulch over them.

Check your mulch when it arrives. Sometimes, when you order a huge mulch delivery, it may come with ants.

Methods of Killing Ants in Mulch

How do you get rid of ants in mulch bag? Below are effective methods you can employ.

Pour Boiling Water

Pouring boiling water on mulch is the fastest method of getting rid of ants on mulch.

The aim is to eliminate the queen ant so that she stops reproducing. Since she never leaves the colony, you’ll have to kill her inside. Boil a kettle of water and scrape the top of the anthill away. Pour the hot water down the anthill.

As long as the queen ant dies, the ant colony dies too because there is no queen to reproduce.

Use Beneficial Nematodes

There are many beneficial nematodes, but only the Steinernema carpocapsae works well. You can buy it at an organic chemical shop, and they come in a sachet suspended in a paste.

Mix the paste with water and spread the nematodes around the nest. Over time, you will notice a significant reduction in the ant population, but you won’t see the dead ants because nematodes disintegrate insects from the inside.

The ant population reduction happens in 3-7 days, but it will take 2-4 weeks for maximum results. 

Keep the soil moist for several weeks because nematodes need moisture to be active. It is also best to use the nematodes immediately when they are most active.

Spread Diatomaceous Earth

You can use baby powder if you don’t have food-grade Diatomaceous Earth. Diatomaceous earth (DE) is a talc-like powder made from fossil remains of marine phytoplankton and is also added to grains during storage.

The powder dehydrates ants and other pests. This method works best in shallow ant nests. The powder may not reach the nest’s bottom if it‘s too deep, or the ants may create another exit.

Use Peanut Butter Poison

Peanut butter works well on big-headed ants, pavement ants, and little black ants. Such ants love protein, sugar, and oil, so this is an effective bait.

Mix a tablespoon of sugar with a spoonful of peanut butter and borax. Push the mixture into a few straws and place them near the ant colonies. The peanut butter will attract the ants, but the borax will kill the ants.

Try Boric Acid

According to an animal study, Boric acid kills ants by eroding their outer shell and stomach. The acid kills certain worker ants and the queen within three weeks.

Make a solution by mixing ½ teaspoon of Boric acid, eight teaspoons of sugar, and a cup of warm water. Saturate cotton balls with the Boric mixture and place them strategically around the mulch.

Since ants love sweetness, you can mix the powder with something sweet like maple or corn syrup to attract them.

Opt for Commercial Pesticides

All pesticides don’t work on all pests. Pick the right one for ants by looking at the ingredients. If it contains bifenthrin, it’s suited for killing ants. Ant pesticides come in liquid or granule form.

If you can’t find a bifenthrin spray, use a carbaryl or pyrethroid spray.

Don’t spray insecticide on the mulch. Spray around it because it might kill beneficial organisms. Remember not to use pesticides if you have pets or children.

Use Commercial Ant Bait

Ant baits are the easiest ant control commercial products to use.  You need to place the bait where there are ants. Worker ants will take it to their nest and share it with the rest of the colony, followed by the death of the whole colony.

Commercial ant bait is available in gel, liquid, paste, and granular forms.

Barrier Sprays

Barrier sprays prevent ants from crossing over into your mulch. Spray the area around the mulch and watch as the ants start to die when they come in contact with the barrier spray.

A plant-based insecticide is best because it will leave a residue that still acts as repellent until the next time you use the barrier spray again.

Natural Methods of Repelling Ants

You can also use the methods below to repel ants in mulch bag.

Use Orange Peels

You don’t see ants around citrus fruits like oranges, grapes, and lemons because citrus fruits repel them.

Boil peels from five or six oranges until soft. That takes 15 minutes. Put the peels and the water in a food processor and blend well. If you have mulch infested with ants, spray this mixture on the mulch. Homeowners have gotten great results from using orange peels.

Introduce Bug-Repellent Plants

Most ant-repellent plants are herbs you need in your garden for medicine or cooking. Examples of these plants include:

  • Lavender
  • Mint
  • Thyme
  • Evening Primrose
  • Marigold
  • Rosemary
  • Catnip
  • Tansy

Apart from these herbs, you can plant garlic because it protects your mulch from pests. If you have large armies of ants in your garden, they will not die from coming in contact with these plants, but the plants will repel them.

Use Peppermint

Ants dislike the smell of peppermint, and so do other bugs like mosquitoes. Incorporate 10-20 drops of peppermint oil with two cups of water and spray around the mulch.

Alternatively, you can soak cotton balls with peppermint oil and place them where the ants frequent. Do this regularly because the peppermint smell won’t last long.

Neem Oil

If you have aphids in your garden, ants will probably be there because they feed on aphids. Applying neem oil will remove the aphids, and the ants will search for another food source.

Neem oil may not be an effective method of eliminating ants in mulch bags. It works best when combined with other methods.


Mix equal parts of vinegar/water, then put the mixture in a spray bottle. Ants usually leave pheromone trails to find their way back or alert other ants that there’s food.

They will not be able to find their way back when you mask their pheromones with vinegar.

Other natural methods of repelling ants are:

  • Dish Soap Solution – This is another easy homemade solution. Mix a teaspoon of dish soap with a pint of warm water, shake the spray bottle well, then spray around the mulch beds.
  • Ground pepper – Black or red (cayenne) pepper deters ants because of its smell. Make sure you grind it well before sprinkling it around the ant areas.
  • Tea tree oil – Mix 5-10 drops of tea tree oil with two cups of water in a plastic bottle and spray around your mulch.
  • Cinnamon oil – Cinnamon leaf contains trans-cinnamaldehyde, which kills and repels ants. Dip cotton balls in cinnamon oil and place them in the ant nest.
  • Lemon eucalyptus oil – oil from the lemon eucalyptus contains citronella that also repels flying bugs and ants. Sprinkle in and around the ant nest or saturate cotton balls and place them in the nest.

Which Ant Species Can Invade My Mulch?

More than 10,000 ant species grace the earth, but the most common mulch invaders are:

Rover Ants

Rover ants measure less than 1/8 of an inch in size and feed on sweet things. Killing these ants with sweetened bait is easy.

Fire Ants

Fire Ants have the most severe bite and usually nest outdoors. They are very aggressive when you want to rid them of the mulch.

Carpenter Ants

Carpenter ants enjoy insect secretions from aphids and will invade your mulch to capture the aphids.

Odorous House Ants

These ants nest outdoors under mulch, logs, stones, and debris. They generally prefer somewhere with moisture. 

How To Keep Ants Away From Your Mulch

Below are preventive ways of keeping ants away from your mulch.

  • Before placing any mulch on the surface, check for signs of existing ant nests and destroy them. You can pour boiling water down their nest to kill the queen and worker ants and stop further reproduction.
  • Discourage ants from building their colony in your mulch by keeping the mulch layer to a maximum of two to three inches.
  • Check the mulch for dark red, orange, or brown sap. If you are using bark mulch, avoid trees like eucalyptus and pine. Use cedar which has a strong smell that repels ants.
  • Keep your citrus plants healthy. Citrus plants infested with aphids will attract ants because they feed on the substance secreted by the aphids. Your mulch will be their hiding place.

Why Do I Have So Many Ants In My Yard?

Ants in mulch bag alone? Probably not. Ants invade a yard when they realize it provides a constant food supply. Some of these food sources include:

  • Honeydew – Garden pests like mealybugs and aphids produce a sweet substance called honeydew which ants feed on.
  • Pests – Ants feed on small insects like termites and fly larvae. They also feed on injured or dead insects.
  • Vegetation – Ants eat decaying or living plant matter. Army ants travel in armies and eat grass as they move.
  • Trash – Ants are attracted to breadcrumbs, sweet foods, or grease. If your yard is not tidy, they will camp there.
  • Moisture – Ants will settle near a moisture source. That includes puddles, leaking pipes, or items that collect water like toys or gardening pots.

How To Prevent Ant Infestation in Your Yard

You will likely find ants nesting in the soil, under yard debris, wood, house siding, and bricks.

If you can’t find them in these places, you can look for mounds of dirt, or you can check for aphids because where there are aphids, ants are probably nesting nearby.

When ants invite themselves to your yard, don’t let them stay. Here are tips to help you eliminate them:

  • Eliminate pests and honeydew – Carefully examine your plants for signs of honeydew-producing pests like aphids, mealybugs, and psyllids which attract ants.
  • Eliminate moisture – Don’t let any water gather in your yard in puddles or pieces of plastic. Keep your gutters clean and repair or replace leaking pipes.
  • Tidy up your lawn – Mow your lawn regularly, pick up all food articles and ensure your bin is tightly shut to prevent ants from entering.
  • Use a repellent barrier – Use a plant-based insecticide to spray your yard’s perimeter. Not only will it kill ants on contact, but it will also leave a residue that still acts as repellent until the next time you use the barrier spray again.

Final Thoughts

Killing ants in mulch bag is possible using methods like Boric acid, Diatomaceous earth, beneficial nematodes, boiling water, and bifenthrin pesticides.

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