What Are These Bugs in the Swimming Pool?

If you’re lucky enough to swim outside most of the time, you’ve likely noticed the human swimmers don’t always have the pool to themselves. Indeed, there are many insect interlopers who find their way into the pool.

Whether they’re drowned and floating in the skimmer basket or buzzing around as you ready to jump in for a workout, these bugs can be a nuisance. But what are they and do they pose a threat?

Here are some of the most common types of bugs you’re likely to find in the pool and unpack whether they present any health or safety risks.

Ewww! What is That?!

If bugs gross you out—and rest assured, you’re not alone if they do—you may be wondering what the heck some of these weird arthropods are that visit the pool. Some of the most common insects that find their way into and around American swimming pools include:

• Ants
• Bees and wasps
• Flies, including house flies, greenhead flies and horse flies
• Mosquitos
• Spiders
• Water bugs, such as boatmen and backswimmers

Are These Bugs Dangerous?

Although some of the bugs commonly found in swimming pools may not directly pose a significant risk to swimmers, others can potentially cause health or safety concerns. Here’s what to know about what risks each of the common bugs listed above pose:

Ants

Black ants may be attracted to pool areas, particularly if there’s a source of food nearby, such as a snack bar that’s not kept adequately clean. Usually more of a nuisance than an actual threat, ants can deliver an unpleasant bite that you’d probably rather avoid.

Fire ants, which can be red, brown, or black, swarm and deliver coordinated painful bites. They’re common in most southern states and nest in grassy fields and most types of soil. Be sure to check before putting your swim bag or towel down near any landscaping features at your pool.

Bees and Wasps

A warm summer day, an open can of soda, and suddenly there are yellow jackets everywhere—this is the story of summertime at the pool.

Bees, hornets, and wasps of all types are attracted to sweet things like sugary sodas and nectar-full flowers. They can build large hives or nests that, once established, can be very difficult to eradicate. 

If these flying pollinators feel threatened, they may attack, and those stings can cause pain, redness, and swelling in just about everyone. For those who are unlucky enough to be allergic to the venom their stings deliver, these interactions can lead to anaphylactic shock and death in short order.

If you know you’re allergic to bees, steer well clear of them and carry an Epi-pen in case you’re stung. If you’re swimming outside in a place where bees might frequent, let your coach and teammates know of your allergy and how to best help you if you do get stung.

Flies

The average housefly isn’t likely to hurt you, but these buzzy bugs can get annoying. They seem to show up any time there’s open food containers or something else odoriferous they’re interested in munching.

Though horseflies, greenhead flies, and other large biting flies aren’t generally regarded as dangerous to humans because they don’t transmit diseases that can harm us, they can all give you a painful, itchy, irritating bite. And when they swarm, you’ll likely need to head indoors until the wind shifts and pushes them to another location.

An infected bite from any of these winged eating machines, however, can pose a danger. If you do get bitten, wash the area with soap and water and apply an over-the-counter antibiotic ointment. If the area becomes very red and swollen, it could be infected—check with your health care provider about next steps, such as an oral antibiotic.

Mosquitoes

Mosquitoes carry various diseases, including malaria, Zika virus, chikungunya, Eastern Equine Encephalitis (Triple E), and dengue fever—all of which can cause very serious illness or even death.

West Nile virus, while still fairly rare, is the most common mosquito-borne disease transmitted in the United States; the Department of Health and Human services reports that about 2,200 cases are reported each year. About 80% of people who are infected with the virus will not develop any symptoms. Of the remaining 20% or so who do develop symptoms, those are typically flu-like. An unlucky 1% or so develop serve West Nile neuroinvasive disease (WNND), which can be deadly or lead to long-term disability.

Other mosquito-borne viruses are less likely to interrupt your swim as they’re far less likely to be transmitted here in the continental United States. According to the Centers for Disease Control and Prevention, since 2019, there have been no reported cases of Zika virus transmitted within the United States. Of the five cases of the virus that have been confirmed in people in the U.S. since 2022, all of those were travel-related, meaning the person picked up the virus when traveling outside the country.

Dengue outbreaks do occasionally occur in the continental United States, the CDC reports, but these tend to be quite rare and well contained. Again, most cases of dengue reported in the U.S. were transmitted by mosquitoes while the person was traveling to a country where the disease is more common.

Malaria was declared eliminated from the continental United States in 1951, but more recently, it has staged a small comeback, though the CDC still notes that “the risk of malaria in the Unites States is very low.” Approximately 2,000 cases of malaria are reported in the U.S. annually, and most of those are in people who’ve traveled to areas where malaria is endemic.

Although swimming itself isn’t a significant risk factor for accumulating mosquito bites or a mosquito-borne virus, mosquito bites can be super annoying and more likely to occur near the pool or lake. That’s because mosquitos breed in standing water. Depending on how the property is landscaped around the pool and if rainwater is allowed to collect in any shallow areas, such as inside empty plant pots, that can increase your risk of encountering them. Also, if you’re hanging out near the pool or standing water during dawn and dusk when mosquitos tend to be most active, that can also increase the chances of collecting some bites.

Wearing mosquito repellent and avoiding lingering around standing pools of stagnant water at dawn and dusk are typically your best ways of reducing the risk of being bitten.

Water Bugs

Some water bugs, such as backswimmers and boatmen, are quite likely to show up at the pool. These “true bugs” in the order Hemiptera, use a rowing or swimming motion to skim across the water.

Backswimmers can deliver painful bites if handled, causing irritation and discomfort. Boatmen, on the other hand don’t generally bite. Both types of bugs can fly and stay underwater for up to six hours, thanks to a clever anatomical air tank of sorts in the abdomen. They can survive the winter, and some remain active under ice.

In either case, these water bugs don’t pose any disease transmission risk and in fact make good eating in some Egyptian and Mexican dishes. Still, it’s best to avoid them if you can. Skimming the pool and removing any blocked skimmer baskets can prevent them from interfering with your swim.

Spiders

Spiders love to build their webs near damp areas like pools because these spaces also attract their favorite foods—flying insects such as mosquitoes and flies. Most spiders that you’ll find around swimming pools, such as the spindly-limbed daddy longlegs and the hairy wolf spider, might be scary-looking but are generally harmless.

Nevertheless, certain species of spiders can deliver painful bites that can result in localized reactions or, in rare cases, severe allergic reactions. These bites also provide an opportunity for infection, so keep an eye on any spider bites you might pick up and talk to your doctor if it appears to increase in redness or size over time.

Bug-Proofing the Pool

Good pool and grounds maintenance is the key to keeping excess populations of bugs at bay and out of the pool. The following tips can help make that a little easier:

1. Maintain the pool and its equipment at optimal levels. Pools that have good circulation, are kept clean, and always have the right balance of chemicals are less likely to develop algae, which can attract bugs and help them establish breeding grounds. The pool should be regularly skimmed and vacuumed to remove debris and the chemicals must be checked and balanced regularly.
2. Use a pool cover. Cover the pool when not in use to keep debris and insects from getting into the water. The cover should fit tightly to minimize gaps these creepy crawlies can squeeze through.
3. Install screening. In some locations, adding a screen enclosure around the pool may be necessary to keep bugs out of the pool area. Mosquito nets can also help prevent insects from getting into the pool area and establishing a home base.
4. Remove standing water. Many types of bugs love shallow pools of standing water, and the longer such pools exist, the most likely you are to develop a mosquito or other buggy population. Be sure to remove any sources of standing water around the pool area, such as flowerpots, buckets, or birdbaths, to discourage mosquito breeding.
5. Hire a pro. In some cases, you may need to hire a professional to eliminate an established bug infestation. For example, if you’ve got wasps building a nest near the pool, it’s a good idea to bring in a professional pest control company to remove the hive. Pest specialists can also help you understand how best to bug-proof the pool to prevent future infestations.