Mosquitoes get into your house through gaps you probably haven’t noticed, and some species actually prefer living indoors. The good news is that once you understand how they’re getting in and what’s keeping them around, the fixes are straightforward. The two big factors are entry points (doors, windows, damaged screens) and water sources inside your home that let them breed without ever going outside.
How Mosquitoes Get Inside
The most common entry point is simply an open door. Every time you walk in or out, mosquitoes near the entrance can follow you inside, drawn by your body heat and the carbon dioxide you exhale. But even with doors closed, they find their way in through surprisingly small openings.
Torn window screens are an obvious culprit, but the less obvious gaps matter just as much. Worn weatherstripping around door frames, especially where you can see daylight peeking through, is a welcome sign for mosquitoes. The gap beneath your door is another common entry point. If you don’t have a door sweep, or if the existing one is worn down, that sliver of space is more than enough. Gaps around window-mounted air conditioning units, mail slots, and pet doors all serve as entry points too.
The American Mosquito Control Association recommends 16-to-18 mesh screening on all windows, doors, and porches. If your screens are coarser than that, or if they have even small tears, mosquitoes can slip through. Run your hand slowly along the edges of every screen in your home. Frames that have pulled away from the track or have gaps at the corners are just as problematic as a visible hole.
They May Be Breeding Inside Your Home
Here’s the part most people don’t realize: mosquitoes don’t always fly in from outside. Some species, particularly the yellow fever mosquito (Aedes aegypti), actively seek out human homes and lay eggs in standing water indoors. As little as a quarter inch of water is enough for mosquito larvae to develop.
Common indoor breeding sites include:
- Flower vases and plant saucers: Water that sits unchanged for a week becomes a nursery.
- Lucky bamboo containers: A classic overlooked source, since the water is rarely changed.
- Pet water bowls: Especially if left sitting for several days.
- Clogged drains: Shower drains, floor drains, and sink traps that hold even a thin film of stagnant water can support larvae.
- Condensation trays: The drip pans under refrigerators, dehumidifiers, and air conditioning units collect water quietly.
French drains and lawn drains connected to your home’s drainage system are particularly common breeding sources. If these systems are clogged or damaged, water pools inside the pipes. You can install fine mesh screens under drain covers to block mosquitoes from entering, but the real fix is making sure water flows through and doesn’t sit.
Some Species Prefer Living Indoors
Not all mosquitoes are the same. The ones you typically encounter buzzing around a pond at dusk behave very differently from the species that thrive inside homes. Aedes aegypti has evolved alongside humans and actually prefers indoor habitats. Buildings offer protection from wind, temperature swings, and predators, while also providing a steady supply of people to bite. These mosquitoes are active during the day, not just at dawn and dusk, which is why you might notice bites in the middle of the afternoon while sitting in your living room.
Culex mosquitoes, the type most associated with West Nile virus, are more likely to enter homes at night, attracted to light and carbon dioxide. They tend to rest in dark, quiet corners during the day: closets, under furniture, behind curtains. If you’re finding mosquitoes in these spots, you’re likely dealing with Culex species that flew in from outside.
Winter Mosquitoes Are Real
If you’re finding mosquitoes in your house during cold months, you’re not imagining things. Some species overwinter as adults, tucking themselves into basements, garages, storage rooms, and crawl spaces where temperatures stay mild. Indoor heat and humidity create conditions that let them survive for months. They enter during fall when temperatures start dropping outside, then go mostly dormant until they sense warmth or carbon dioxide from a nearby person. At that point, they can reactivate and bite even in January.
Basements are the most common overwintering spot. If yours is damp and cluttered, it’s essentially a mosquito shelter. Reducing humidity with a dehumidifier and sealing basement windows can cut down on winter visitors significantly.
How to Get Rid of Them
Start with the water. Walk through every room and eliminate any standing water you find. Change flower vase water at least twice a week. Flush drains that don’t get regular use. Empty and refill pet bowls daily. Check under sinks and around appliances for condensation puddles. For drains that tend to hold water, a bacterial larvicide (available at hardware stores) kills larvae without posing risks to your plumbing or household.
Next, seal entry points. Replace damaged screens, install door sweeps, and apply new weatherstripping where gaps are visible. For screen doors that don’t seal tightly, hook-and-loop tape along the top and sides creates a much tighter fit.
For mosquitoes already inside, household aerosol sprays containing pyrethrins provide immediate knockdown. Close doors and windows before spraying, keep them shut for 5 to 10 minutes afterward, and only use products labeled for flying insects. The major limitation of these sprays is that they don’t provide lasting protection. They kill what’s in the air at that moment, but new mosquitoes that enter later won’t be affected.
A simple box fan near where you sit can also help. Mosquitoes are weak fliers, and moderate airflow makes it difficult for them to land on you. Electric indoor traps that use UV light or carbon dioxide lures can reduce numbers over time, though they work best as a supplement to sealing and water elimination rather than a standalone fix.
Why It Matters Beyond the Annoyance
Indoor mosquito bites aren’t just itchy. Mosquitoes that live and bite inside homes can transmit serious illnesses, including dengue, Zika, chikungunya, and West Nile virus. The species most adapted to indoor living, Aedes aegypti, is the primary vector for dengue and Zika. Because these mosquitoes bite during daylight hours and prefer to feed on humans specifically, people who have them breeding inside their homes face repeated exposure.
Mosquito-borne infections range from mild fever and joint pain to severe complications including birth defects from Zika and, in rare cases, fatal encephalitis from West Nile. The risk varies by region and season, but the basic calculus is simple: fewer mosquitoes in your house means lower exposure to every disease they carry. Eliminating indoor breeding sites is the single most effective step, because it breaks the cycle rather than just reducing the number of adults temporarily.