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

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

(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

Picture of 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

Picture of 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

Picture of 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

Picture of 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:


pooter1433 made it! (author)2015-08-30

Good on you for giving GreenPowerScience and Dan Rojas credit for the inspiration. I saw his video at least a year ago but never made the mosquito trap. Thank YOU for reminding me and inspiring me to finally make one. My 5 year old daughter just completed this simple but awesome project. We can't wait to go back out and see how many blood suckers we caught! Thanks NightHawkinLight :)

Pandroe (author)2015-08-27

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

Cmddx1 (author)2016-07-07

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

RadarRon (author)Cmddx12016-07-08

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.

JaredL16 (author)RadarRon2017-07-31

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

maxhuey (author)2016-07-20

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...

thundrepance (author)2016-07-09

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

DeboraD (author)2016-07-07

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

SirPython (author)2016-07-07

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?

SirPython (author)2016-07-07

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?

FlyinngDolphin (author)2016-07-07

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.

PlanetaryGear (author)2016-07-07

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!

Epimethius (author)2016-07-07

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.

tb55chevy (author)2016-07-07

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.

JoeV24 (author)2016-03-08

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

rafununu (author)2015-10-09

Any fan can fit ?

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

keith & BonnieR (author)2015-09-04

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

glennell (author)2015-09-03


schengnz (author)2015-08-30

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.

JamesF24 (author)schengnz2015-08-31

First off, simply applying a voltage to the screen will NOT kill bugs. If you examine a bug zapper, you will see that there are TWO screens with a high voltage applied between them. When the bug passes through (between) the screens there is enough of a breakdown of the air path resistance to allow a short term arc between the screens that fries the bug. The reason that applying a voltage to a single screen like in this "instructable" will not work, is for the same reason that birds can safely land on the very high voltage power lines and not get fried.

LDM1 (author)JamesF242015-08-31

Aren't those power lines insulated?

Tkdwn (author)LDM12015-09-03

Yes, insulated with air! :D

JamesF24 (author)LDM12015-09-01

The only insulation coated wires are from the pole to the house, the 120v or 240v feed that is usually wrapped around a support strand for aerial feed. The top wires between poles are bare wires that are air insulated from each other by separation. During really humid weather you can hear them crackling and trying to break down the air insulation.

Another example closer to the ground... an electric fence. It is a single electrified strand. If you stand there in bare feet and touch it you provide a good path to ground and will get zapped. Put on some rubber boots and no zap.

For a bug to get zapped on an electrified screen of the mosquito catcher in this 'instructable', it would have to try to step off and touch something grounded. An idea might be to add a fan to a regular bug zapper, sucking in bugs and frying them.

qdogg (author)LDM12015-08-31

Power lines aren't insulated. That's why they're up high where you can't touch them or underground in thick tubes.

KeithM9 (author)schengnz2015-08-30

A little zap might burn bugs onto a metal screen. I don't like the water idea either. I see it better to just keep them trapped for a while until they die

mid_life_crisis (author)2015-09-01

I find myself wondering if the screen is absolutely necessary. If skeeters are that delicate, wouldn't just getting pulled through the fan do them in? Just curious.

NachoJ (author)2015-08-31

LOL. When I first saw the picture and the description I thought you were making a Hill Billy technology bug zapper. But now I see the simplicity and beauty of your 'ible. Very nice. Just don't let the kids near those battery leads. ;) And I'm making one for my deck. (Sans battery)

pmshah (author)2015-08-31

Why not simply attach a large 12 V instrument fan n line with a bug zapper. The ones available here in India are very close to Tennis racquets in size and shape. These have 3 screens separated by sort of plastic grill such that the outer ones do not touch the middle one which is at close to 400 v with respect to the outer one. Of course the energy stored by the capacitor at this voltage is very low so a human only feels a slight zing.

raviolikid (author)2015-08-30

What a great 'ible! do you really just run this out in the open and it takes care of the bugs or is it just for use in the tent? I guess this explains all the fans sitting outside that I have seen on my full-time adventures! I guess I should have just asked!

Yeah I run it out in the open and it works great

Swell! I am going shopping at the end of summer sales and pick me up one! Next year, I will ENJOY Michigan!

rfitzgerald (author)2015-08-30

Great idea :) and upgrading to a 12v fan would be a good idea. Out of interest how long does your battery last on a full charge? I wonder if a car radiator fan would be suitable for the job, maybe with a variable resistor to lower the speed/noise/power usage.

Others have suggested radiator fans, that's a good idea. I haven't ever run a battery dead with the fan so I don't know how long it would last in total, but I've had it running for a good 6-8hrs without slowing down.

That's incredible the battery has lasted that long, most fans of this size (at least in the UK) consume around 45-60 watts, then you've got the inefficiencies and overheads of the inverter itself which is likely 80-85% efficient at best, you must have a decent battery :) Most inverters will just cut out once the battery is drained down to a certain level so you wouldn't normally see a slow down at all (and for the safety of any devices you might use with an inverter you'd hope it doesn't slow down). That's very good going though and if it meets your needs then no real need to upgrade. IT's good that you mentioned about modified sine wave inverters and motors too. I'm not too knowledgable on the subject but from my experiences the motors normally run fine but the inverters themselves tend to go pop, I've got through a few low powered ones over the years but recently upgraded to a 1000w pure sine wave model (only a cheap Chinese one from ebay though). I think the general rule of thumb when sizing inverters for use with a motor is to go for one at least double the rating of the fan as motors use a huge amount of power when starting up but once it is running at full speed the power usage drops considerably. Anyway I'm rambling now so I'll leave it at that :) we are due to be going camping next week and mosquitos are always a problem where we go so I'll be sure to try out your project myself too.

mdblocher (author)2015-08-30

Thinking of this for my patio, without the battery and inverter. Should the fan be

blowing away from people or toward them?

If the fan is blowing toward people that will help to keep bugs away instantly, but in terms of capturing them it doesn't matter where it's pointed.

nanaverm (author)mdblocher2015-08-30

The air should be blowing toward people, since mosquitoes don't like airflow and it might discourage those that avoid the fan trap from biting you. This trap will suck them onto the screen from the other side before they can get to you to bite from the front.

mdblocher (author)nanaverm2015-08-30

That is what I was thinking, but wanted confirmation.

HalH1 (author)2015-08-30

This is a great idea. You could also use it at home on those nights when you want to sit outside and just relax. I've been watching Dan and Denise Rojas for several years now. They have produced some great videos in just about every green category you can think of. Green Power Science is on YouTube, and we will probably be seeing the results of this excellent video in a campsite near you :-)

jpridgen1 (author)HalH12015-08-31

Dan and Denise are awesome! I've been watching them for years now also!

jpridgen1 (author)2015-08-31

Big fan of NightHawkInLight and Dan Rojas here! Im going camping this weekend and will be taking this along with us. Check out both of these guys Youtube channels tons of cool stuff!

SmittyInPhilly (author)2015-08-31

We have been camping for years and know the best way to enjoy sitting outdoors w/o bugs is to have a light fan blowing on you. The constant air keeps the bugs away. Especially if you don't have time to build a mosquitoes trap. I like the 50% alcohol and safe eating idea. Thanks for sharing.

MikeC72 (author)2015-08-31

I understand that Mosquitos are relatively weak in flight and minor breezes get them all screwed up. A good sized fan blowing on you should keep most of them so disoriented that they won't be able to land on you. The fabric trap is a good bonus and I suspect they will die in short order once pinned on it. If you're worried about survivors, a few sprays of Windex should put them out of their misery ... that works great on flies. The muffin fan ideas below sound good in theory but I think the kill rate would be proportional to the area of the fan ... size does count.

ymasullo (author)2015-08-31

Clever and simple.

Kathys Smokin (author)2015-08-30

This looks fantastic……simple, cheap and effective. I'm tired of those expensive Mosquito Magnets that work for a year or so and then die. My family loves the idea of a fan blowing cool air on them while sitting outside in summer heat, too. Thanks so much for posting your friend Dan's work, NightHawkInLight.

BlackSheep0ne (author)2015-08-30

How tough would it be to take the fan grate(s) off and line both with screen (or maybe with very fine nylon netting, since it would be somewhat protected by the grate)?

KeithM9 (author)BlackSheep0ne2015-08-30

The fan grates are easy to remove since they are held in place by 6 short screws, although I dont think it would be a good idea to put the screen under the grate because it is very flexible and could get caught on the fan blades.

kirk thill (author)2015-08-30

This sounds like a good trap. I was a mosquito/vector control technician for about 20 years and we used small CO2 traps (dry ice) as an attractant. These traps also use a very small light bulb to help steer the mosquitoes to the trap. The CO2 was the main attractant, but the small light bulb might be a easy addition to this trap.

courtervideo (author)2015-08-30


metqa (author)2015-08-30

I use the same idea in my house. Works well on fungus gnats and fruit flies as well

About This Instructable




Bio: I like turning boring things into awesome things! Usually on video.
More by NightHawkInLight:How to Make a Produce Slicing Shotgun Barrel for Air CannonsLarge Bore Vacuum CannonFitzroy Storm Glass (18th Century Weather Prediction Device)
Add instructable to: