Bugs Attracted To Air Conditioners – And How To Keep Them Out

People seek refuge from the summer heat by keeping their air conditioners on. But during the hottest times of the year, air conditioners are an attraction for various bugs, especially in nighttime warmth.

An air conditioner’s moisture and warmth attract certain types of bugs. Cockroaches, spiders, mosquitoes, flies, fungus-gnats, hornets and centipedes can enter the condenser grill, vents or ductwork for temporary shelter, food, moisture or to lay their eggs.

If your home has become a bug community during the summer, several methods can prevent the bugs from entering your air conditioner. This article explains how air conditioners are a prime attraction to bugs and what to do about it.

Why Bugs Enter Air Conditioners

Summer is an excellent season for bugs to reproduce and to find easily accessible shelter and food. Cockroaches, spiders, mosquitoes, flies, and hornets are the most common bugs seen during the summer months.

Most insects prefer a moist environment, and unfortunately, an air conditioner is a perfect place for these bugs to dwell.

Whether a spider or a flying cockroach, most bugs survive on three primary factors:

  1. Food
  2. Water
  3. Shelter

An air conditioner offers a perfect habitat for bugs. With its warm compressor, cooling water, and excess heat, it’s difficult for bugs not to live in it. 

However, with a little effort it is possible to prevent bugs from entering your AC unit. After all, no one likes seeing bugs and insects inside their home, especially in their AC or HVAC system.

Relationship Between Bugs and Moisture

Most bugs prefer living in sweltering temperatures and moist conditions, and here’s how your AC provides them with their ideal environment:

  • Extreme moisture inside the AC unit provides a suitable environment for bugs to breed. Research has shown us that humidity significantly affects egg hatchability, with more eggs produced the higher the humidity.
  • During summer, you’ll notice the tell-tale AC puddle of water near every home. The water dripping from your AC or HVAC system builds an ideal habitat for bugs that like to hatch their young in water, such as mosquitoes or dragonflies. Bees and wasps can also often be seen using the drip/condensate pipe for a drink.
  • Many bugs not only use air conditioners to gain access to the moisture, but as a freeway into your. home to access food.

Bugs That Are Attracted To Air Conditioners

While some bugs can nest inside the compartment of your air conditioner, others die when they don’t find their way out. The following are the seven most common bugs found in your air conditioner:

1. Spiders

Spiders are flexible bugs. They can squirm their way into the small holes and cracks inside the air conditioner. Spiders may quickly get into the compressor, ductwork, expansion valve, and vents of your AC/HVAC system.

Spiders typically don’t cause any technical damage to the AC system. However, they pose a significant health hazard.

Many spiders have strong venoms, such as the Brown Recluse or Black Widow, that can get dispersed into the air you breathe if they enter your air conditioner.

Spraying commercial insecticides is an excellent way to prevent spiders from entering your air conditioner. Unlike other bugs, spiders are solitary living, so you may only have two or three intruders.

2. Centipedes

The reason you see centipedes in your house is the same as for other bugs: they come seeking shelter, warmth, water, food, and a nest to lay their eggs. Where is a better place for them to reside than your AC system?

Centipedes search for most AC and HVAC systems’ moist, shady, and dark environments. The condenser’s grill is a commonplace in the air conditioners for centipedes to live.

The whirring movement and fresh water from the condensation are the main attraction for centipedes. However, an air conditioner with plenty of water, warmth, and dead insects makes it difficult for centipedes to enter or survive.

3. Cockroaches

Among other bugs, cockroaches are the most attracted to your AC/HVAC system. Heat, water, and darkness are the three primary factors for cockroaches to enter anything. Unfortunately, an air conditioner provides an ideal habitat for cockroaches to thrive.

An air conditioner is a confined unit that makes it perfect for cockroaches to nest and hide from predators, even during the wintertime when the unit may not be in use.

Cockroaches are not picky eaters, and they will eat almost anything. Therefore, if your air conditioner is not frequently cleaned, it can be a good place with ample food for cockroaches. Dirt, hair, dust, and dead insects are common food sources for them in the air conditioner.

4. Gnats

Gnats are not primarily attracted to AC or HVAC systems. The fungus gnat is the only type of gnat attracted to the air conditioner due to its high moisture content. The air conditioner’s compressor and evaporator have significant moisture, serving as the primary attractions for gnats.

Gnats mostly enter the air conditioners for shelter and breeding purposes. If they breed inside your air conditioner, you may experience moisture problems in your HVAC system. 

5. Mosquitoes

Mosquitoes can come through the filters and vents of air conditioners, but they are not actually attracted to air conditioners. This is because mosquitoes don’t prefer staying in an environment with a freshwater supply or moisture. Instead, they like the humid and warm atmosphere of a stagnant pool of water – such as that provided by the condensate pipe outside your home.

Mosquitoes neither die nor stay alive around an AC or HVAC system. Instead, they become inactive. Exhaust vents and air vents of the HVAC system are common compartments for mosquitoes to come through. Therefore, they do not reside in or enter the air conditioner but are simply attracted to the outside of the unit.

6. Flies

Flies can come through any crack or hole they find, and a window air conditioner or its vent are perfect pathways for flies to enter. If your AC system is not installed or sealed correctly, it can become a home for flies.

Drain flies are among the common flies attracted to an air conditioner.

Flies can only pass through the system. They cannot reside or breed in the air conditioning system. The extreme water supply and warmth can kill them.

7. Hornets

Hornets and wasps are attracted to air conditioners. AC and HVAC systems, ducts, and air conditioning units offer a moist space and water supply suitable for hornets to nest.

AC compartments’ confined and dim nature provides a secure area for hornets to protect themselves from predators.

The internal units of the HVAC system are great for hornets to gain warmth. The water trap on the air conditioner consists of a sweet liquid that entices hornets to get in.

Do Different Types of Air Conditioners Attract Bugs?

Bugs can enter, live, or pass through air conditioners, but there is a difference between the different types of air conditioners and how they attract bugs:

  • Central Air Conditioners. These large cooling systems contain ducts and split mechanisms to supply cooling air to your home. The ducts generate warm air and steam through a whirring mechanism. Unfortunately, this makes it a perfect space for spiders, cockroaches and flies to live and breed.
  • Portable AC Units. These are another great attraction to bugs. Due to their low energy consumption, bugs like cockroaches and hornets can easily live in them. These air conditioners also take the moisture and warm air from the environment to their compressors, providing suitable conditions for bugs to nest.
  • Window AC. It provides a prime gateway for bugs to enter. Flies, mosquitoes, and gnats can readily travel through tiny cracks and holes around the window AC.
  • Split Unit AC. These ACs can also help bugs enter your home through the tube connecting the outdoor split system to the indoor duct.

Many bugs find the vent and condenser grills a great place to nest and shelter. These grills allow bugs to move inside the interior duct and tubes to get the warm heat.

How to Prevent Bugs From Entering Air Conditioners

The entrance of any bugs inside your air conditioner can lead to some technical disaster (not just bugs being in your home). In rare cases, it can even cause a complete function failure of your AC or HVAC system.

Fortunately, there are some practical and valuable ways to prevent bugs from entering or coming through your air conditioner. These include:

Seal Cracks Around the Ductwork and Vents

Bugs can move throughout your home through ducts and vents. Once they make their way into your home, preventing them from living in your air conditioners can become pretty difficult.

The best way to prevent this is to ensure that the ducts have no cracks or holes. You need to also seal all the twisted or tilted parts of the duct and vents.

You can also install a fitting screen over the vent and duct opening. The screen will be a barrier to keep the bugs away from your air conditioner. These screens can also prevent birds and insects from building a nest on the duct.


Another practical way to prevent the bugs from entering your air conditioning system is to mow the area around the condenser.

Whether it’s a small fence, decorative plants, or bushy shrub, keep them 3-5 feet away from the AC condenser. This way, your condenser will have enough space to operate.

Greenery, dirt, debris, and dust can often invite bugs to dwell in the condenser. Due to the highly efficient and continuous functioning of the condenser, make sure you landscape the area frequently. 

Chalk the Gaps

Even if there are no cracks or holes around your AC or ductwork, make sure to chalk it. Bugs are highly flexible animals, so they can wriggle their way out of small holes.

Chalking the area around your air conditioner and the split system is easy to prevent bugs from forcibly entering.

Build a Rocky Garden

The shrubs and greenery may increase the attractiveness of your space, but they will also invite various bugs. Condensers near or around shrubs can easily attract many bugs and insects.

If you want to keep your condenser in its prime condition, set up a rock garden around it. This way, you can dissuade the bugs while ensuring there are no plants that could block the condenser’s coil.

Get Rid of Stagnant Water

A stagnant puddle of water dripping from the duct or AC is another attraction for bugs like gnats, flies, mosquitoes, and hornets. Organic and waste material around the puddle can build up quickly, encouraging bugs to live, eat, and reproduce.

Make a habit of removing any standing water or puddle around the AC or condenser. If there are potholes in the ground around the condenser, fill them with hardware chalk or dirt.

Clean the Central AC Unit

The central AC unit tends to get wet and dirty as it operates frequently. The dirt, dust, debris, and moisture piling up on the central unit can lure bugs like cockroaches, gnats, and spiders to build their home.

A poorly maintained central AC unit is an absolute haven for bugs.

It’s important to vacuum and frequently clean the unit’s filters, fan, and blades.

Schedule a Bug Maintenance

If you think there is any technical issue with your air conditioner because of bug nests, schedule a professional bug maintenance session for your AC or HVAC system. It will remove every dead insect, food residue, and nest.

This is great at the start and end of the summertime at the very least.

Do Air Conditioners Keep Bugs Away?

An air conditioner does not prevent bugs from entering a home. However, the cool, dry air it generates can discourage insects from living in the home.

Bugs prefer warm temperatures with humid conditions. An air conditioner and its parts, including the condenser and compressor, provide optimal temperature and environment for bugs to reside.

Can Bugs Get Through an Air Conditioner?

Bugs and insects can easily enter an air conditioner and home through the condenser’s grill, vents, and ducts. Most air conditioning systems provide suitable shelter, food, and reproduction conditions for bugs.

Condenser’s grill, vents, ductwork, and tube are common places for bugs to nest. They can even make their way into your home through these parts.

How Do I Bug-Proof My Air Conditioner?

Nobody likes having bug invasions in their air conditioning system. But if you have noticed bugs residing in your air conditioner or its parts, there are several easy and practical methods to bug-proof your air conditioner, including:

  • Installing screen on vents and ducts
  • Sealing the split system
  • Chalking the corners around the HVAC system
  • Keeping the condenser space clean

Russell Singleton

Russell holds a Bachelor of Science (Environmental and Marine Geoscience) with Class I Honors. He is currently completing his doctorate in science and is passionate about all earth processes, especially isotope geochemistry and paleohydrology.

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