(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: https://www.youtube.com/NightHawkInLight