How to Stop Bugs from Coming Through Window Air Conditioner

UV and white light are like beacons to insects of all kinds and the light inside your home are no different.

Of course, bugs can’t reach that light by passing through your window, however, if there’s a tiny crack or a small opening through an A/C window unit perhaps, it might as well be a welcome gate thrown wide. 

Bugs can be a serious nuisance and it is not a problem at all for even the larger of the various species of insects to wriggle through the tiniest gaps in the framework of an A/C unit, make their way through the system itself, and ultimately, into your home. 

It’s not just moths either. Bed bugs, cockroaches, mosquitoes, spiders, flies, gnats, and more than we could probably list without becoming largely redundant.

Besides, when spiders are infiltrating your A/C, there’s really not much left to discuss. To help you get things under control, we will cover the following:

  • How are the insects coming through the A/C window unit
  • Why insects are coming through your A/C window unit
  • Will these insects set up shop inside your window unit
  • Type of insects that are likely to come into your home
  • How to get rid of them
  • How to prevent them from coming through your window unit

How are the Insects Getting In?

You’ve mounted your A/C unit, placed the adjustable accessory flaps in just the right spot. You can’t detect a single sliver of sunlight coming through the crack because the seal looks immaculate, right?

Unless you seal the entire unit into the window with caulk, silicone, expanding foam, or something similar in functionality, those pesky little insects will find a way.

Many insects, such as cockroaches, have flat and nearly collapsible, exoskeletons, which allows them to force their way into the smallest of spaces.

They also like to come in through the air vents, as there has to be a flow of air from outside to inside, chilled in between. If air can pass through, you can bet that several insects can do the same. 

It’s a common urban legend that people swallow several spiders in their sleep throughout the year. Whether or not that’s true, you can bet that if you have a window unit, that’s how they got in. 

Why are Insects Coming in Through the Window Unit?

Insects are just like people. They’re social, crave warmth and protection, food and water, supplies and shelter.

Light may be the initiating factor but it’s ultimately the warmth and instinct for safe harbor. Unsecured food can certainly exacerbate the situation as well.

Bugs are instinctively attracted to UV light or white light and it’s quite common to have a bright light on inside of a room that has a window unit installed.

Under normal circumstances, they can’t get in. However, with a window unit, it’s merely an unlocked door. 

These insects are known as Phototactic insects and they are drawn to the light inexorably. The problem is, no one knows—frustrated scientists included—what draws insects to light and away again when it is dark. 

If you own fluorescent lights or those extra bright, energy-efficient light bulbs, the insects will come every time you turn them on.

If you want to attract fewer bugs, you’re better off going with a yellow light bulb, as in the good old, energy-sucking variety.

Insects also prefer the cooler air on summer days and nights. They will naturally gravitate to cool spots, such as your window unit.

While they may not have intended to infiltrate your home, trying to cool off will bring them there nonetheless. 

Will Insects Nest Inside Your Window Unit?

Certain insects will perhaps. Cockroaches and centipedes prefer the more normalized temperature of the inside of your house, rather than a constant blast of icy cold air but they won’t hesitate to go through your fully operating window unit to get there. 

For the most part, insects prefer warm and moist areas, a source of food and water, and shelter so they can expand their own little brood.

In all likeliness, your window unit will serve as a mere passage, rather than a new home. 

Types of Insects That Will Come in Through the Air Conditioner

The size of the openings dictates what kind of insects will try coming into your home the cold way.

Cockroaches are your absolute worst offenders, mostly because it’s easy for them to crawly up to and then through your unit or through imperfect seals. 

Cockroaches are notorious for their ability to squeeze through extremely flat spaces, such as beneath baseboards, and over the top of crown molding that is nearly flush against the ceiling.

Their exoskeletons are designed that way. 

Cockroaches can breed quickly. The German Cockroach female lays what is called an ootheca and each one can hold around 15 to 25 eggs.

When you consider that a single female can do this multiple times per year and many more times over her lifespan, you can see where that will lead. 

In the summer, mosquitoes, flies, and spiders are the worst, with the first two being the most prevalent by far, probably because nature deemed it necessary to have larger numbers of them.

On any given summer night, there are probably one hundred times as many mosquitos as spiders for every square foot. 

Flies are a vicious nuisance as well, however, and if there is an opening, they will exploit it.

They also breed in insane numbers, just like cockroaches, so once they are inside, it’s important to get rid of them quickly. 

How to Get Rid of Them

You can do so by natural means or by professional means, whichever suits you best, however, if natural methods don’t work, your best bet will be with a professional exterminator. 

Natural Methods

Most insects loathe peppermint oil, lavender oil, cayenne pepper, and Diatomaceous Earth. Well, they don’t really loathe Diatomaceous Earth; they just get it all over them and it cuts them to pieces whether they like it or not. 

Peppermint, cayenne pepper, and lavender are easy to spread around, especially diluted in water. You can place them in a sprayer and cover all of the areas where they like to spend the most time. 

Diatomaceous Earth and Borax are perfect for cockroaches, as you can mix either one with sone sugar, place it on a dish, and let the roaches come to the sugar.

The Diatomaceous Earth is razor-sharp and will stick to the exoskeleton of a roach. 

As it returns home, it spreads these little crystals around, each one cutting through their exoskeletons, taking them apart, absorbing the water within the roaches, and eventually incapacitating them or dehydrating them.

Either way, they’ll die. 

Diatomaceous Earth also works against other insects, such as fleas, bed bugs, all varieties of roaches, and beetles.

The best way to distribute it is to sprinkle it anywhere near ingress or egress points throughout the home, under sinks, window sills, cabinets, and anywhere else insects may congregate. 

Professional Exterminator

Of course, if things get too rowdy, you should always call in an exterminator. They’re going to be a little bit better at locating all of the insects, their hiding spots, and their ingress and egress points. 

Also, the stuff that they put down will last for an extended period of time.

They’ll also help your resolve your window unit A/C as well, by either helping you seal it or putting chemicals in a place that will keep insects well away. 

They can also give you advice on how to deal with infestations and how to cover all of our bases in terms of keeping the insects out for good. 

How to Keep Insects Out of Your Window Unit

As aforementioned, insects come into your home for a lot of reasons. Food and water top the list, but shelter and cooler air certainly help.

The best way to deal with them is to properly seal your window unit, then systematically remove the things that attract them. 

  • Use caulk or silicone to seal the window unit and the expandable folds
  • Thoroughly clean the room(s) in which your window unit(s) are located
  • Ensure that there are no nearby sources of water or moisture
  • Go through all of your drawers, closets, and corners with a vacuum

The best way to get rid of insects is to get rid of the things they want. It’s like the saying goes, “the best offense is a good defense.”

The best defense, in this instance, is to seal your window unit by going over every crack and crevice with a caulk gun.

Once you have cleaned out the room(s) and removed all sources of exposed water, you’ll have successfully removed all of their incentives. 

Final Thoughts

Insects may be the most disgusting thing in your universe but they are only ever after the same things that you are, which are food, shelter, and water.

If you do your best to seal your window unit and remove all of those temptations, you shouldn’t have to worry about anything more than the occasional visit. 

Alright, that’s it for this article, here are a few hand-selected articles that you might also find interesting reads:

How To Stop Bugs Coming In the Window At Night (Easy Checklist)

How I STOPPED Pill Bugs Getting In My Home

How I STOPPED My Neighbors Roaches Invading My Apartment!

Steve Foster

Mad about bugs and wanting to publish as many articles as I can to help educate people about these amazing beautiful creatures! For more info check out my about page

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