How to Get Rid of Mosquitoes With a Fan & Window Screen




Introduction: How to Get Rid of Mosquitoes With a Fan & Window Screen

About: I like turning boring things into awesome things! Usually on video.

(The video embedded above demonstrates how I made this trap, and written instructions are included below)

When I first learned of this mosquito trap from my friend Dan Rojas (check out his YouTube channel here) I had really low expectations. The function is apparent enough in that it's just meant to suck mosquitoes up against a screen and hold them there, but I didn't see how that would really do much good in reality because there's no bait to attract them. I was wrong.

While camping last year in an area where the mosquitoes were particularly bad even for a Michigan swamp, I remembered this trap and just happened to have a 12v marine battery and power inverter in my truck. After the first night of biblical level buginess I took a trip down to the closest hardware store and picked up a $15 box fan and some window screen to give it a try. Upon first arrival to this camping spot it was a challenge to not inhale mosquitoes on every breath. By the end of the second day running this fan trap the local population was down to the point of only swatting one or two away in an hour. Very impressive results.

Step 1: The Fan

The box fan I used for this trap is nothing special. Similar fans can be found in any hardware store or supermarket. The size is about 2' x 2', and I imagine larger or smaller fans would work as well so long as they move enough air to trap the mosquitoes (it doesn't require a lot).

The first step will be to rotate the fan so it's blowing away, and the side that pulls air is facing forward. You can see in the above image how blades of grass are pulled up against this side of the grate.

Step 2: Screen

The next step will be to get yourself a piece of window screen large enough to cover the face of the fan. Any type of window screen is acceptable, but I prefer aluminum because it seems like it should stand up to the elements longer than plastic or fiberglass.

The screen is then attached to the fan's grate, pressing as close to it as possible. When I first made this trap I held the screen on with duct tape and that did a fine job, but it looked messy. I've upgraded now to using zip ties as the images demonstrate.

Step 3: Capturing & Exterminating

With the screen attached the trap has been fully assembled! It couldn't be any simpler of a design. With the fan turned on mosquitoes seem to be drawn right out of the woodwork to start collecting on it's surface. My theory is that their primary attraction comes from investigating the fan's motion. Unlike moths and gnats mosquitoes are not attracted to light, so adding illumination like a bug zapper does no additional good. This trap attracts mosquitoes, and only mosquitoes.

Once a significant number have collected, an environmentally friendly way to kill them off is to give them a mist of diluted rubbing alcohol. The alcohol is diluted to a 50% concentration with the addition of water so that it's no longer flammable and you don't risk catching the fan on fire. After the mosquitoes have died off and are brushed from the screen the alcohol evaporates and what remains behind is safe for other forest creatures to eat.

If you're not comfortable misting liquids on a running fan (I've never had any issues with it) I'm sure you can think of other creative ways to deal with the mosquitoes once they've been captured.

Step 4: Power Supply

Finally, here is the power inverter and battery that I use to run this trap when I'm far back in the woods. Nothing too special. The inverter is 200w. Ironically, a fan is one of the few electrical items you're not supposed to run off of a small inverter like this because the AC waveform it generates is bad for a fan's motor, but the fan has been going strong for over a year. I figure if it dies on me it's paid for itself many times over by now. Perhaps an upgrade would to simply purchase a fan that's made to run directly off of DC power and skip the inverter altogether.

Thank you for reading! If you would like to see more of my projects I often post them on my YouTube channel a while before they make it over to Instructables. You can find my channel here:

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73 Discussions

I made something similar. I was pleasantly surprised at how many mosquitos were trapped! Well done 'ible!

1 reply

I understand mosquitoes are attracted to the carbon dioxide we exhale. They find us by following our breaths. Perhaps the fan also draws in our CO2 clouds and the little buggers follow our breaths to their doom.


2 years ago

Couldn't the alcohol hit the motor and potentially explode.

2 replies

If you dilute 50% alcohol with 50% more of water the solution will not ignite even if sprayed directly into an open flame. On the other hand I would caution about spraying any liquid into a "powered" motor though. Too much liquid may cause an electrical short. So with some common sense and a fine misting you'll be fine.

I pressure washed a box fan, then dried it out with a leaf blower before using it, and it's fine.

when we were travelling in Asia, living in a hot and humid room next to a stagnant canal with billions of mosquitoes breeding, we left a 12" fan just inside the small window blowing air in to cool the room, the next morning we found thousands of dead mosquitoes on the desk where the fan is located. Mosquitoes just love the sound of the fan blades flapping though the air. they fly close to it get hit by the fan blade and died instantly on the table. No they did not get chopped up...

my son & i will make these for my house & his apt, as we are mosquito bait! x^b

What a simpe way to take care of a big problem! Thank you!

Why do you need to the screen face? Couldn't you just leave the back open, so when the mosquitoes are pulled in they just get chopped up?

Why do you need to the screen face? Couldn't you just leave the back open, so when the mosquitoes are pulled in they just get chopped up?

There is nothing complex in that simple box fan motor to be damaged by a modified square wave inverted. It is a relatively low wattage system.

A salvaged auto radiator fan is a very high current draw motor and would quickly run down your battery.

The cheap box fan is a very well designed energy efficient system for moving air. I do not think you could have developed a more energy efficient system.

I may try a mini bug vac system for my home using a 6 inch computer fan. I would use a light to attract other bugs.

You may want to research COW VAC, a system for removing flies from dairy cows.

You don’t actually need to spray anything to kill them, just leave the fan running and the airflow will desiccate them and kill them over the next few hours. Thats how those fancy propane burning mosquito traps kill them. I’m going to build one of these tonight and give it a try!

Sources of 12V fans: A car radiator fan uses 12V and is high flow. They are in various sizes and $19 to $40 new. You could get them for less from a car recycler. Purpose-build 12V fans for RV cooling are $19 to $150.

Great ideas.I will wrap the 120v fan on our deck with screening - that should do it.

Something to try I did this in a similar fashion but using an inexpensive furnace filter for when I was painting to filter the air. I took small binder clips and attached them where the fans cover screws are. I replaced the screws with longer ones and small washers clamping one of the arms of the binder clip in it. then I pressed on the other to open the clip and slip in the cheap filter, this could be done on this project also to hold the screen and no need to worry about clipping to the fins.


2 years ago

What's missing is the tiny screams of terror from the mosquitoes. That would be a nice addition.

Any fan can fit ?

Cos cars fan work in 12V and can be found in any car breaker, so no need for the inverter.

Great Video. I am definitely going to try this. My husband works for a 4H Camp and this Summer he was covered in bites. The kids were too. We have tried all sorts of sprays, lotions & homemade solutions, but still come away with bites. This is a great option to use in our cabins. Most of them use fans to circulate the air so this would help in two ways. 1. Cool air flow 2. Get rid of the mosquitoes that sneak in the screen door. Thanks for your video. Look forward to more.


Bonnie Russell

Would it work with a regular (say every 5 mintes) high voltage low current zap across the aluminium grill to kill off any trapped mosquitoes? That way there would be no need for regular attention or risk of water shorting out motor.