9 Surefire Ways to Control Ants in the Compost Bin

If you’re like me, you love composting. It’s a great way to reduce and reuse your waste and create nutrient-rich soil for your plants in the bargain.

But I’ll admit, I had to go against my initial instincts when it came to leaving insects and other crawling critters in the compost.

straw over compost in winter to keep it moist
Fine pieces of straw help keep the compost warm and maintain adequate moisture

I wanted to torch them like any other pests! As I learned how helpful they are to the composting process I made peace with the bugs, worms, and all the other “helpful” organisms.

However, one of the biggest challenges I’ve faced when composting is keeping ants out of the bin.

Ants are rarely helpful for your compost, usually doing more harm than good. Once they get a foothold they can quickly overrun the contents and generally make a mess of things.

But not to worry: In this article I will tell you about nine proven ways to control ants in your compost bin. So read on, and learn how to keep your compost ant-free.

What’s the Problem with Ants?

At first glance, having ants in your compost bin might not seem like a problem at all.

After all, there are plenty of insects and other life forms that are beneficial to the compost pile, speeding up the breakdown of biological matter and excreting compounds that will help our compost nourish plants and soil.

It seems like ants would be a perfect fit in this self-contained little ecosystem. They eat biological matter, they tunnel, and generally do all the other things that beneficial insects do.

So why do they get the bad rap? Why are we trying to boot them out of our compost bin and keep them out?

In short, ants are rarely a net positive for the compost pile and are often disruptive to processes we are trying to encourage.

Yes, ants do tunnel throughout the compost and this will help with aeration somewhat, which is good, but many species of ants are nothing less than an organized nuisance.

Ants often prove to be highly predatory to the other organisms that we want living in the compost!

Ants working in concert can massacre pretty much anything that they can catch, given enough time, and having them exterminate the other insects and organisms in the compost pile is only going to slow us down from reaching the finished product.

Accordingly, if you notice a serious congregation of ants moving in, through, and around your compost bin, it is time to take action.

Ants in my Compost! What did I do?

9 Surefire Ways to Control Ants in the Compost Bin

1. Keep It Turned

A great method to control ants in your compost bin is simply to keep the compost turned. This accomplishes two things:

  1. it aerates the compost which speeds up decomposition.
  2. it collapses and tunnels exposes any egg chambers that the ants might have been established in the bin.

This is, as you might imagine, greatly disturbing to the ants and forces them to relocate.

Turning your compost is something you should be doing regularly anyway, but I mention it here because it is not only important for the overall health and production of the compost but also for reducing the infestation of pests, like ants.

Turning is also something you’ll want to do in tandem with other methods on the list as a sort of one-two punch since it will make most methods of repelling ants easier and more effective.

But even if you don’t want to add any chemicals or other substances to your compost when starting out, simply turning it regularly will go a long way towards disrupting the ants before they establish a sizable colony.

2. Keep It Moist

Another common composting step you should be doing anyway: One reason ants might be attracted to your compost bin is if the conditions are too dry.

Ants need some moisture to survive like most creatures, but they prefer to build (and build quickly!) in dry soil.

Moist soil and other materials generally confound their efforts to establish the tunnels that service the colony and provide them a place to live.

If your compost is too dry they might see it as a potential option for setting up shop and decide to move in.

You can avoid this by maintaining proper moisture levels in your compost bin.

This means adding water regularly, but making sure that the bin is also well aerated so that excess moisture can evaporate and escape.

If you do this, ants will be less likely to see your compost as a potential colony site and will likely avoid establishing themselves in your compost.

The ideal level of moisture in your compost bin that is suitable for discouraging the activities of most species of ant is “definitely damp”.

If you take a handful of compost and try to press it together in a small ball or clump, it should mostly stick together without being an oozing mess.

If the compost is somewhat sticky to handle and easily binds to itself, that means most ants are going to have a difficult time excavating it and tunneling through it.

3. Put a Good Lid on Your Bin

This one is pretty simple. If you have a good, tight lid on your compost bin, it will be harder for ants to get in. This is especially true if the lid fits snugly and has no cracks or holes in it.

It is possible to sort of retrofit an existing lid that has a sloppy fit using weather stripping, tape or even caulk to produce a snug, almost gasketed seal.

Necessary because ants, as you know, are quite tiny and can slip into even the smallest openings.

A well-sealed bin will also help with moisture retention, which we talked about previously. So not only will it be harder for ants to get in, but the compost itself will remain less attractive to them as a potential colony site.

Now, this technique does have some drawbacks, namely the fact that a compost bin that is sealed up too tightly will not allow for adequate evaporation of moisture content which can lead to mold, rot, and other problems.

That being said, it is entirely possible to drill some holes in an existing, tightly fitted lid and then line the interior with fine mesh that will provide ventilation while keeping ants and other critters out.

4. Bury Your Food Scraps

Food scraps from your kitchen are an invaluable additive for your compost bin, but they might be the chief attractant of the ants you are trying to get rid of!

Ants have excellent olfactory receptors and can “smell” food from a long way off.

When you toss food scraps on top of your compost without turning them under, you’re basically advertising free chow to the ants, and believe me they will come looking for it.

But by burying your food scraps deep in the compost bin, you make it harder for them to be detected by ants and less likely that they will end up being dragged back to an ant colony.

You can also put a layer of dry leaves, grass, and other plant matter over the buried food scraps to further disguise its odor and hopefully help prevent ants from detecting it.

This is another good method to use in combination with other “non-additive” methods, since it will make your compost increasingly unappealing to the little critters.

5. Use Natural Ant Repellants

There are a number of plants and other substances that ants find repulsive. Whether they are irritated by them directly or these substances disrupt their pheromonal communication or pathfinding efforts, we aren’t quite sure.

But a mountain of evidence suggests overwhelmingly that they do work! In fact, you’ll be happy to learn that several excellent options are probably found in your kitchen right now.

Natural solutions with a good track record include wood ash, crushed eggshells, sage, spearmint, and peppermint.

Crush up any of these into a fine powder or flakes and place them in a tight perimeter around your compost bin, either on the ground or immediately inside the container.

Several of these, particularly eggshells, spearmint, and peppermint, can also be added directly to your compost when you turn it to distribute this ant-repellent effect throughout the compost.

Even better, you can add any or all of them without harming the beneficial microbes, earthworms, and other insects that are working to break down the organic matter in the pile.

6. Diatomaceous Earth

A highly effective way to control ants in your compost bin is to add diatomaceous earth directly to the compost.

This natural substance doesn’t really look like earth at all, being white in appearance and looking similar to pumice powder or clumped baking soda.

Here’s a fun fact for you: diatomaceous earth is made from the fossilized remains of diatoms, a specific group of microalgae. Interesting!

But now for the really interesting part. Diatomaceous earth is a highly-effective, all-natural insect killer and is particularly effective against any insect with an exoskeleton.

This is because it is mildly abrasive, but more importantly, has properties of absorption that will strip the outer layers off of an insect’s shell.

Though the shell itself is hard enough to resist the abrasion, once they lose that outer barrier that holds in their body moisture, they basically dry out and die.

Definitely a brutal way to go for the little guys, but undoubtedly effective!

Diatomaceous earth has been used this way for a very long time in all sorts of climates and against all sorts of insects, and it is widely used today for insect control in the storage of dried grains.

It will work just as well when added to our compost bin. A couple of scoops, some vigorous turning, and you shouldn’t have to worry too much about ants in your compost bin anymore.

One word of caution, though. This stuff affects most insects and arthropods, not just ants. That means there are quite a few beneficial species that could be taking up residence in your compost bin that will perish along with the ants.

Compared to other pest control additives, though, it is totally organic and all-natural so if you’re forced to resort to a “nuclear option” this is one of the better ones.

7. Pesticide

When you have no other options, or the ants have gotten totally out of control, it might be time to switch to the big guns.

Modern chemical pesticides will kill ants essentially on contact and can help to get the situation in your compost bin under control quickly.

There are a number of different pesticides that you can use, but make sure to choose one that is safe for use around plants and on crops.

You don’t want to end up with poison in your compost that could make its way into your food.

Your best bet is going to be any pesticide that is approved and safe for use on vegetable crops.

There are quite a few, but two of the most common that are also extremely effective are pyrethrin and carbaryl.

Right out of the gate, if you were going to go with one of these try to use pyrethrin. It is highly biodegradable and steadily breaks down when exposed to strong UV light.

It will not persist in the soil and for that reason will not accumulate, reaching stronger and stronger concentrations, over time if you are forced to dose your compost bin more than once.

However, if you require greater effectiveness for a truly substantial ant infestation, consider carbaryl.

This stuff is decidedly toxic to humans and other mammals, but it does not accumulate in fat or other body secretions and is rapidly eliminated from the body over time. Full disclosure, it is classified as a likely carcinogen for humans, however.

As you might expect, pesticides are equal opportunity killers. It will kill the ants, along with all other insect, arthropod, and crustacean life in the bin.

This can further set back the necessary processes in your compost.

Trust me, there are plenty of insects and other organisms in there that you want to stay in there! But, sadly, sometimes desperate times call for desperate measures.

The most important thing to remember when using pesticides is to be careful.

Make sure to follow the directions on the label and take all necessary precautions with personal protective equipment and application procedure to avoid harming yourself, your family, or your pets.

8. Add Parasitic Nematodes

If the ants prove too persistent and too numerous to deal with in any other way, and you want to stop just short of declaring total war with pesticide, there might be another option.

In warm weather, usually mid to late spring, you can add parasitic nematodes to your compost pile.

What is a parasitic nematode? Although it sounds like a monster from some cheesy late-night sci-fi movie, it mercifully isn’t that bad.

Actually, it might prove to be that bad for the ants! Parasitic nematodes are tiny, microscopic worms that infest and kill ants, and the ants have basically no defense against them.

These are easily obtained at well-stocked garden supply centers and you can sow them in your compost bin ahead of time to prevent ant infestations or to eliminate an existing infestation.

Even better news? Although it sounds kind of hideous in principle these parasitic nematodes are in no way harmful to your compost, to you, your crops, or any pets, so you need not worry about unwanted side effects.

9. Install a Moat

Lastly, although it won’t do much to help you against a raging infestation that is already in your compost bin, one of the best and easiest ways to keep ants out is to install a moat around your bin.

Ants cannot cross water, and will reliably drown or be swept away in any amount of standing water.

If you take a small, dish-shaped container or hollow ring and place it around your compost bin you can fill this with just a couple of inches of water and you can rest assured that ants will not be able to cross it.

This is one of the least invasive, safest, and most effective methods for preventing an ant invasion.

There are some drawbacks to this method, namely that you have to stay on top of keeping the moat filled with water or it won’t work at all.

But in conjunction with other, minimally invasive ant control methods, this is a completely green and environmentally friendly way to keep the ants at bay while preserving all of the other helpful organisms in the bin.

Keep the Compost, Lose the Ants

These are just a few of the many ways you can control ants in your compost bin. With a little effort and some experimentation, you should be able to find a method or combination of methods that works best for you and your situation.

Don’t let those pesky ants keep you from maximizing the returns on your composting efforts.

What are some of your favorite methods for controlling ants? Let us know in the comments.

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