Can mosquitoes get through window screens? Not through intact mesh, only through the holes, tears and gaps that a damaged screen leaves open.
Total Screen repairs and rescreens window screens across San Diego, so click here to contact Total Screen, today.
In this guide, we will explain where a window screen actually fails, what the numbers on screen mesh mean, and what a no-see-um screen adds.
A screen only works while it holds its shape, so get mosquito screens installed before the next warm spell.
Can Mosquitoes Get Through Window Screens?
An intact window screen keeps mosquitoes out of a home, and the CDC's advice is simply to use screens on windows and doors.[1]
The CDC pairs that advice with one instruction: repair holes in screens to keep mosquitoes outdoors.[1]
A mosquito does not chew, cut or force a way through screen mesh.
Anyone asking can mosquitoes get through window screens is usually looking at a screen that already has a problem.
Landing on a screen is not the same as getting past one.
A mosquito finds an opening that is already there.
The question is never whether the weave can stop a mosquito, but whether the screen still holds its shape.
A screen that still holds its shape gives a mosquito nothing to use.
Where A Window Screen Actually Fails
Torn mesh is the most obvious failure, and the one the CDC names.[1]
A tear does not have to be large to matter.
A screen frame that sags away from the window leaves a gap along the edge.
A tear is the failure everyone pictures, and it is the only one of the four that is actually a hole.
A gap at the frame lets mosquitoes in as reliably as a hole in the mesh.
Loose spline, the rubber cord that holds the mesh into the frame, lets the mesh pull away at a corner.
A screen door that no longer closes flush leaves a gap down the latch side.
How To Check A Window Screen In Two Minutes
Checking a window screen takes about two minutes, and needs nothing but a light.
Hold a light on one side and look from the other, because a hole shows up as a bright pinpoint.
Run a finger along each edge of the frame and feel for a gap.
Press gently on the middle of the mesh and see whether the mesh has gone slack.
Check each corner, where loose spline lets the mesh lift first.
A screen that passes all four checks is still doing its job.
What The Numbers On Screen Mesh Mean
Screen mesh is measured in threads per inch, which is all the numbers in 18×16 describe.[2]
A standard 18×16 mesh carries eighteen threads one way and sixteen the other.[2]
Standard mesh is what most San Diego homes already have, and standard mesh stops mosquitoes.
Strands or threads, the number on a mesh label is just how many cross one inch.
A higher thread count packs more threads into the same inch, so the openings come out smaller.
20×20 is the next weave up, and 20×20 is built for insects a mosquito screen was never sized to stop.[2]
Total Screen installs both weaves.
Does A No-See-Um Screen Keep Out Smaller Bugs?
Standard window screens do not stop no-see-ums, and the CDC says so plainly.[3]
The CDC's wording is that many commonly used window and door screens do not have holes small enough to prevent biting midges from getting inside.[3]
A biting midge, the insect behind the no-see-um nickname, is usually less than an eighth of an inch long.[4]
A midge that size walks through a weave a mosquito cannot, which is what the finer mesh is for.
The CDC's own recommendation is to look for mesh screens measuring 20×20.[3]
A no-see-um screen is that 20×20 mesh, sold under the name of the insect it was woven to stop.
Phifer, the manufacturer, calls 20×20 a 15-to-20 percent tighter weave that keeps out most smaller flying insects, like no-see-ums, gnats & sand flies.[5]
Which Mesh Should You Ask For?
For mosquitoes alone, a sound standard screen is enough.[1]
For no-see-ums, gnats or sand flies, 20×20 is the figure to ask for.[3]
The County of San Diego names a fine mesh specifically for the small Aedes mosquitoes, the tiger mosquito better known here as the ankle biter.[6]
Held to the light, the finer weave is the one you can see the difference through.
Total Screen measures every opening before building the screen, because the fit decides whether the weave ever gets tested.
A screen cannot help with mosquitoes that are already inside, which is what how to get rid of mosquitoes in your house covers.
Get Your Screens Checked Before The Season
When mosquitoes come out in San Diego sets the deadline, and a screen check belongs ahead of the first warm week.
The second-best time to check your screens is today.
Total Screen repairs, rescreens & replaces window and door screens across San Diego, often with a same day or next day appointment.
A rescreen ends with every opening in the house back to holding its shape.
Call Total Screen at (619) 871-7610 for a free on-site estimate.
Or click here to fill out our 2-question contact-form, and we'll get in touch right away.
Can mosquitoes get through window screens? Only where a screen has stopped being one.
Let's get every opening in your home back to holding its shape.
Disclaimer: Total Screen is not a mosquito-control or public-health authority. This article is provided for informational purposes only, and is based on our online research of publicly available documents from the Centers for Disease Control and Prevention, the County of San Diego and the other sources listed below. To report a mosquito problem, or to ask about treatment on your property, contact the County of San Diego's Vector Control Program.
Sources
- Centers for Disease Control and Prevention — Preventing Mosquito Bites (“Use screens on windows and doors. Repair holes in screens to keep mosquitoes outdoors.”). cdc.gov
- Metro Screenworks — guide to screen mesh (mesh count = threads per inch; 18×16 standard, 20×20 no-see-um). metroscreenworks.com
- Centers for Disease Control and Prevention — Preventing Oropouche (“Many commonly used window and door screens do not have holes small enough to prevent biting midges from getting inside”; “To prevent biting midges from entering your home, look for mesh screens measuring 20x20”). cdc.gov
- Centers for Disease Control and Prevention — Meet the Midge (biting midges “usually less than an eighth of an inch (3mm) long”; “much smaller than a typical fly or mosquito”). cdc.gov
- Phifer — Bug Protection (“15 to 20 percent tighter weave than standard insect screening”; keeps out most smaller flying insects like no-see-ums, gnats and sand flies). phifer.com
- County of San Diego, DEH — Invasive Aedes Mosquitoes (“Use a fine mesh to prevent the small Aedes mosquitoes from getting in”). sandiegocounty.gov