Ants in Compost? What Attracts Them, Benefits & Solutions

Those composting for the first time are likely to encounter many creatures in their heap or bin. Some of these are beneficial; some are not so desirable.

Ants are one common compost critter many people worry about, but are they really a problem? And what should you do about it if they are?

How do you get rid of ants in compost? Maintain a correct balance of nitrogen and carbon materials, keep moist conditions, and frequently aerate the pile to deter ants in compost. To get rid of ants from compost entirely, drench the area with cold water, add cornmeal to the heap, or using diatomaceous earth or nematodes.

Ants in compost are not in themselves usually a problem and can actually be beneficial. However, if they are a biting kind, you might not want to have them around.

Unfortunately, ants in a compost heap is usually also a sign that your compost is too dry, so the material won’t compost as quickly or effectively. 

In an organic garden, it is generally best to live and let live. However,  you can encourage the colony to move to a less troublesome spot.

To find out more about ants in compost, what to make of this, and how best to handle the situation, read on.

Ants in Compost – Good or Bad?

The first thing to think about when you see ants in your compost is whether this should be viewed as a good or bad thing.

Below, we’ll look at this issue in more depth so you can decide whether you need to do anything about the situation or not.

Benefits of Having Ants in Your Compost

Like all garden creatures, ants have a role to play. In a composting system, while they can be a sign of suboptimal conditions, some ants can be beneficial.

Ants help you compost by:

  • Helping to mix the materials in your bin or heap, so they compost more evenly.
  • Distributing bacteria and fungi through the heap so a healthy composting community takes hold.
  • Shredding materials to make the rest of the job easier for micro-organisms, which can also speed up the process.
  • Aerating the compost as they make their tunnels and chambers below the surface. 
  • Adding fertility through their waste.

Are Ants Bad for the Compost Heap? 

While some ants can bring benefits in composting, you usually don’t want them in your heap.

Frequently, it is not that the ants themselves pose a threat but rather that having ants is a sign that your composting system is out of balance. 

Some ants, however, you won’t want, either because they further imbalance the system or because they are unpleasant for you or even do you harm.

Biting ants do have a role to play in the ecosystem – but you don’t want them in areas of your garden that you will be spending a lot of time in – your composting area included. 

Invasive species and native species of ants will, of course, depend on where you live.

But invasive species of ants are never welcome, and sadly, these are ants that you will want to eradicate before they can damage the native ecosystem in your area. 

Ants in Compost Pros & Cons

Will Ants Kill Compost Worms? 

Army ants, red army ants and carpenter ants not only have a nasty nip, they can also unfortunately decimate the compost worms when present in large numbers. 

Best Ants To Have in Compost

The ants that you should not mind having in your compost are those which eat vegetative matter. These are the ants which can help break down the compost materials.

However, it is worthwhile remembering that in a healthy, balanced heap, ants are unlikely to arrive.

For the best quality compost, take care of the environmental conditions and keep all ants away. They can still provide their natural ecosystem services in other areas of your garden. 

Which Ants Are Not Good for Your Compost? 

As mentioned above, ants that eat worms are certainly not good for your compost.

The ants that kill worms can upset the natural balance of your composting system and leave you without the very useful services which the composting worms provide. 

Can You Use Compost With Ants in It?

No doubt, you will definitely not want to use compost with ants in it in your houseplant pots since you do not want an infestation in your home.

However, seeing an ant or two in your compost is no reason not to use it outside in your garden.

As long as the ants in question are not an invasive or troublesome biting species, you can use the compost on your growing areas and these ants will find a home elsewhere.

If these are not ants you wish to have in your garden then it is best not to use the compost in your garden until the ants are gone. 

Why Are There Ants in Your Compost? What Attracts Them?

Five forest ants walking on a large green leaf.

Ants are attracted to food scraps in compost. Really, any food source can attract them, but ants will only typically arrive in compost that is too dry.

Ants will not thrive in compost that is correctly balanced and moist and humid with higher temperatures.

They will arrive en mass when there are dry conditions ideal for them to make their nests.

These are not conditions that a well-prepared and well-managed compost heap will typically provide. 

How To Avoid Ants in Your Compost

Follow these helpful tips to keep ants from being attracted to your compost in the first place.

  • Make sure your compost is not too dry. Add more water to improve the moisture in the heap or bin as necessary.
  • Add more nitrogen rich (green) materials. A dry heap may be a sign that there is too high a proportion of carbon-rich (brown) materials, like woody materials, dry leaves, straw etc., in your compost. 
  • Turn or aerate the compost. This is essential to make sure there is oxygen in the mix, and disturbing the heap regularly will discourage ants from moving in. See the best aerator options here.
  • Mix up food scraps well with other materials, and make sure they are buried to avoid attracting ants. 
  • Consider fermenting food scraps in a bokashi system before adding them to your main composting system. Learn more about bokashi composting in our article here.

How To Control Ants in Compost 

It is important to remember that a healthy compost ecosystem should be filled with life, and a few ants in your compost is not always a serious problem.

If the ants are a more beneficial type for composting, you may simply wish to control their population rather than getting rid of them altogether.

Keeping the compost wet enough, raising temperatures by choosing a different composting method, or adding more nitrogen-rich materials can all help control ants in compost.

They may still be present in small numbers, but their population will not get out of control. 

Another key thing to remember in an organic garden is that we can keep balance and avoid any one population from getting out of control by attracting more beneficial wildlife to the space.

When we attract predatory creatures which kill/eat ants and keep ant numbers down, we can keep the ant population under control more easily. 

How To Get Rid of Ants in Compost

If the ants are invasive or particularly problematic in the garden, there may be certain times when you wish to get rid of ants in compost entirely.

This can be a lot more challenging than simply managing the ant population in your garden.

Here are some of the strategies that are commonly employed, though as noted below, many also have downsides, and some should definitely be avoided.

Drenching With Water

Drenching with cold water can encourage the ants to move elsewhere, but it will not actually kill them.

Some are tempted to use hot, scalding water to kill ants. Do not do this.

Using hot water on your compost heap will not just kill ants. It will also kill the beneficial creatures you require to compost successfully.

Cornmeal

Some species of ant are drawn to cornmeal and treat it as food but cannot digest it.

If you sprinkle some cornmeal close to an ant nest in your compost, eventually certain ants will eat it and die.

Cornmeal can also be beneficial in your compost, providing food for micro-organisms in the system.

However, it is important to note that this is not effective on all ant species.

You should never add poisons to the bait since if you do, you will kill other creatures and will not be able to use your compost around food production. 

Diatomaceous Earth

Food grade diatomaceous earth (DE) is an organic substance which many use for pest control in an organic garden.

DE is made from the fossilized remains of tiny, aquatic organisms called diatoms. Their skeletons are made of a natural substance called silica.

Sharp particles in this substance will piece through the bodies of insects like ants. This disrupts their internal balance of water and eventually leads to their dehydration and death.

However, it is worth noting that DE can also have a similar effect on beneficial insects in your garden.

So while you may wish to use it in isolated and extreme cases, using it widely might not be the best idea. 

Parasitic Nematodes

Another key strategy in organic gardens involves using biological controls like parasitic nematodes to control pest species.

Certain, specific nematodes can be effective against certain ant species, but it is important to make sure that you know which species you are dealing with and choose the right biological control for your needs. 

Never use gasoline, oil, kerosene, or other harmful fossil fuels on your compost heap. These things will kill ants, but they have no place in an organic garden.

The compost you create will not be usable – especially around food. 

Remember, killing ants to eradicate them entirely is rarely the best option.

This should really only be considered when the ants are an invasive species that will disrupt the local ecosystem if left to proliferate. 

How To Keep Fire Ants Out of Compost

A red fire ant walking along green stalks.

Fire ants and other biting ants can definitely be a problem in a garden where they are in close proximity to people. They really can give a nasty nip.

To keep them out of your compost, the strategies are the same as those for other ant species.

Simply make the compost warmer, wetter, and less favorable environmentally for them, and they are less likely to take up residence. 

How To Get Rid of Fire Ants in Compost

Native fire ants have a role to play in our gardens, even when we find them terrible to have around.

So the best policy is to let them live in areas of the garden where they will not trouble us as much.

However, if you have an invasive species of fire ant, you may wish to consider using cold water, cornmeal, diatomaceous earth, or nematodes to get rid of them entirely.

Do Coffee Grounds Kill Ants?

Coffee grounds do not kill ants, but when lots of coffee grounds are added to a compost heap, this can make the environmental conditions less favorable and encourage ants to keep away.

However, it is not always a good idea to add excessive quantities of coffee grounds to your composting system.

Coffee grounds are an excellent nitrogen source for composting. They have a carbon to nitrogen ratio of 20-to-1.

Informal trials have shown that sustained temperatures of 140-158℉ (60-70℃) for up to two weeks were recorded when coffee grounds were 25% of the material in the compost pile by volume.

So coffee grounds could be used to great effect in hot composting systems.

In a typical cold compost heap or bin, however, coffee grounds should only ever be added in moderation.

Yes, you can add some coffee grounds to your compost heap, but be sure to keep the compost balanced, and add only a little at a time.

Layer coffee grounds and other kitchen waste with carbon-rich compostable materials.

Adding too many coffee grounds in compost at any one time can be detrimental to earthworms and may also kill beneficial microbes in your system. 

Does Vinegar Kill Ants?

Vinegar does not kill ants, though it can be effective in repelling these creatures.

Sprinkling or spraying vinegar in a particular location may encourage ants to move away.

However, like coffee grounds, acidic substances like vinegar should only be added to a composting system in moderation.

Adding too much vinegar could lead to a pH imbalance in your heap, which is detrimental to composting worms and microbes in the system. 

Are Ants Good for the Garden?

Remember, while you might not wish to have a lot of ants in your compost heap, native ant species are a beneficial part of the garden ecosystem.

Ants can not only be helpful in breaking down vegetative material, but ants can also “farm” and herd aphids, which can be used to your advantage in an organic garden.

They are also an important food source for a range of creatures. So where possible, taking a live-and-let-live approach is the best policy.