Ants in My Mailbox: How to Keep Them Out?

Ants can form colonies inside all sorts of structures, including your mailbox! If your post is suddenly crawling with ants, ant larvae and eggs, you need to act quickly to get rid of them.

Several substances (including coffee grounds, various essential oils, soap, pepper, borax and boric acid) can help to keep ants out of your mailbox.

Why are there ants in my mailbox?

Ants may invade your mailbox for a variety of reasons. Like all other living creatures, ants are motivated primarily by three things: food, water, and shelter.

If you open your mailbox one morning to find it swarming with ants, therefore, there’s a good chance that it rained overnight. This is because ants (like many other creatures) are most likely to seek out shelter when the outdoor conditions are cold and wet. You may also see a peak in ant invasions in your mailbox (and house!) during very hot spells of weather when they come in to take refuge in the shade.

Food packages may also draw ants into your mailbox, especially if they’re left in there for a while! If you are in the habit of having edibles delivered to your house, it’s important to check your box regularly for packages to avoid attracting ants – and other critters – inside.

Why should you care if there are ants in your mailbox?

While many ant species are harmless, others can cause big problems for homeowners. Fire ants are notorious for their painful sting, while carpenter ants can hollow out a wooden mailbox post in no time at all.

Even if the ants in your mailbox aren’t biting, stinging or causing structural damage, you’ll probably want rid of them anyway. Receiving bills is never welcome; even less so when they’re covered in bugs.

How to get rid of ants in your mailbox

When rainy weather drives ants indoors, you may find the occasional colony moves in your mailbox. Fortunately, getting rid of them is usually simple, and the first step is to remove the nest. It’s not the most pleasant task, but it must be done!

To get rid of ants in your mailbox you must physically remove the insects, their eggs and their larvae. If your ants are of the biting or stinging variety, it’s obviously best not to do this with your bare hands.

You could don a pair of thick gloves to keep them off your skin, but the safest way to deal with biting ants is with a hose. Turn a high-pressure jet of water on them to blast them and their offspring away (just make sure to remove your post, first).

You can also use an ant killer such as boric acid or borax to exterminate your ants. However, these are not considered safe to use around children or pets, so proceed with caution if you decide to go down this route.

Bundo Kim/

How to keep ants out of your mailbox in the future

Getting ants out of your mailbox usually isn’t difficult, but stopping them from coming back requires a little more work. You can prevent ants in your mailbox by:

Scrub it clean (to destroy ant scent trails)

Ants produce chemicals known as pheromones, leaving a ‘scent’ trail in their wake. Other ants then use their antennae to detect and follow this trail, which allows them to locate their buddies. If you’ve had a recent ant infestation, your mailbox probably reeks of ant pheromones and will attract even more of the insects, leading to recurrent invasions.

To prevent more ants from invading your mailbox, you’ll need to destroy this ‘scent’ trail as soon as you’ve evicted the bugs. Scrub your mailbox inside and out with a solution containing one of the following trail-destroying substances:

  • Soap
  • Bleach
  • Detergent
  • Apple cider vinegar

Apply ant repellent

Once you’ve thoroughly cleaned out your mailbox, you can use ant repellents to stop new colonies from moving in. Chemical ant repellents are widely available for purchase and may be suitable in some situations. However, these formulations may also be toxic to other species, including beneficial bugs (like spiders and ladybugs) and pets.

Fortunately, there is a wide variety of natural, non-toxic, ant repelling substances that can be sprinkled in and around your mailbox to keep ants at bay. These include:

  • Black or cayenne pepper
  • Certain essential oils (such as peppermint, neem, tea tree, lemon eucalyptus, or cinnamon leaf essential oil)
  • Coffee grounds
  • Vinegar
  • Diatomaceous earth
  • Liquid detergent
  • Hand soap
  • Glass cleaner

Vinegar and essential oils (like peppermint, neem, tea tree, and lemon eucalyptus oil) can be mixed with water and applied to your mailbox as a spray. Alternatively, you can soak a cotton ball in the essential oil of your choice and leave it inside your mailbox to deter ants and other bugs.

Other solid ant deterrents (like coffee grounds, pepper, and diatomaceous earth) can be sprinkled inside or around the base of your mailbox post.

Remove any food sources

Keep in mind!

Sometimes, ants are attracted to mailboxes because they find food in there. But this is only likely to be the case if you have packages containing food delivered to your house, which are then left inside your mailbox for extended periods of time.

To avoid attracting ants (and other beasties) remove all food-containing packages from your mailbox as soon as they are delivered, and store them securely in your house.


Finding that your mailbox is suddenly swarming with ants can be alarming; even more so when they appear overnight! Ants tend to seek shelter indoors during periods of cold and wet (or especially hot and dry) weather and are more likely to infest your post at certain times of the year.

Fortunately, there are preventative measures you can take to keep them out. Diatomaceous earth, coffee grounds, pepper, and certain essential oils can all be used to repel ants, while hand soap, detergent, borax and boric acid can kill them stone dead.


Ginny Johnson

I am a rural carrier. All you need to do is leave your mailbox open overnight. People pour powdered poison into their boxes and just leave it there 365 days a year. Concern for pets/children, not for mailman that can’t wash their hands and have to eat in their cars.

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