Introduction: A Cheap & No Maintenance LED Fan Mosquito Trap

About: I'm an interactive installation designer. I like to create playful experiences.

Mosquitoes suck. Literally. They buzz around your face, cause irritating bites and keep you up at night. These pests have to be dealt with. But what’s a practical way to go about it?

There are already some existing DIY mosquito trap designs, but they either flat out don’t work (yeast/carbon dioxide traps) or they work but require unpleasant maintenance (stagnant water for ovitraps).

Enter the LED fan mosquito trap. It’s inexpensive, easy to make, doesn’t require any chemicals or liquids and requires virtually no maintenance. Best of all, it actually works! (see proof in new 4th photo above)

The idea is simple. All it takes is an LED-equipped computer fan with netting strapped onto the back. The LED light draws mosquitoes in close and the fan sucks them into the net. Overpowered by the fan and unable to fly away, the imprisoned mosquitoes eventually tire out and die. Hurray!

It takes about 30 minutes to make your own LED fan mosquito trap. Read on to learn how.

Credit: this design is a refinement of the LED + fan traps posted by user MaruthupandiA and user A_Steingrube

Step 1: Tools & Materials

  • 120 mm fan with embedded LEDs ~ $8-10:
I tried a couple other fan models and this was the only one that pushed enough air to effectively catch mosquitoes:
  • 3-pin ATX to 4-pin Molex pass-through adapter cable ~ $0
Comes with fan mentioned above in #1

  • 2.1 mm x 5.5 mm power pigtail, female ~ $5 for 10

  • Any 12 volt power supply with a 2.1 mm male plug, rated for at least 500 milliamps (0.5 amps) ~ $0-6
I used one I had sitting around. This one should work:

  • Pair of wire strippers
  • Solder, soldering third hand, soldering iron
  • Heat shrink tubing, 2 sizes
Find one tubing that will fit over the individual wires and find another tubing that will fit around all the wires bundled together. If you don't have heat shrink tubing, electrical tape will also work
  • Netting, 12 inches x 26 inches ~ $2
The netting should have holes 1.2 mm or smaller to effectively trap mosquitoes. I purchased netting at a local discount fabric store for $2 per yard
  • 4 small zip ties
Find zip ties that will fit through the mounting holes at the corners of the fan

Total Cost of Materials: ~$21

Step 2: Clip Off 3-Pin Connector

The first step is to clip off the 3-pin connector from the 3-pin to 4-pin pass-through adapter cable.

This 3-pin connector will be used with a 2.1 mm power jack pigtail to create a new adapter cable to connect the fan to the power supply.

You can discard the 4-pin pass-through cable.

Step 3: Strip and Add Solder to Wire Ends

Using the wire stripper, strip off the ends of the 3-pin connector wire and the 2.1 mm x 5.5 mm power jack pigtail.

Next, prime the bare ends of the wires with some solder. This is known as tinning the wires.

Step 4: Position Heat Shrink Tubing & Twist Wire Ends Together

Before joining wires together, trim and position some heat shrink tubing. This heat shrink tubing will protect the wire joints and help prevent them from shorting.

First, place heat shrink tubing over one of the 3-pin connector wires.

Second, place heat shrink tubing over both of the 2.1 mm power jack pigtail wires.

With the heat shrink tubing in place, twist the red wire of the 3-pin connector and the red wire of the 2.1 mm power jack pigtail together. Do the same for the black wires of the 3-pin connector and the 2.1 mm power jack pigtail.

Note: If you don't have heat shrink tubing, some electrical tape will also work.

Step 5: Solder Wire Ends Together & Place and Secure Heat Shrink Tubing

Using a soldering iron, solder the red wires together. Once the joint has cooled a bit, slide the narrower heat shrink tubing over the joint.

Using a heat source, heat the heat shrink tubing until it is firmly in place. I improvised with a soldering iron, however, I recommend using a heat gun if you have one. A pocket lighter will also work.

Next, solder the black wires together. Once this joint has cooled down, slide the wider heat shrink tubing over both joints. Heat this heat shrink tubing firmly in place.

Now the fan to power supply adapter cable is complete.

Note: If you don't have heat shrink tubing, some electrical tape will also work.

Step 6: Wrap Netting Around Fan

Now that the power is ready to go, we can move on to making the net.

Cut out a rectangular portion of netting about 16 inches by 26 inches in size (40 cm by 66 cm).

Fold the bottom 2 inches (5 cm) over itself making a cuff. Do this again so the folded netting is 3 layers thick. This will create a firm bunch for the zip ties to grab onto.

Next, position the fan over the center of the folded netting. Carefully and snugly wrap the folded netting around the perimeter of the fan.

There should now be equal amounts of the folded netting hanging over the front and the back of the fan. There has to be enough folded netting overhang on each side reach and cover the fan mounting holes.

Step 7: Attach Netting to Fan With Zip Ties

With the netting in place around the fan, carefully fold the netting down over both sides of of a fan mounting hole.

Using a knife, pierce through the netting into the fan mounting hole. Do this on both sides of the fan. This creates access holes for a zip tie to pass through.

Carefully insert a zip tie into the front access hole, through the fan mounting hole, and out the back access hole. Cinch the zip tie down securely.

Repeat this step for each of the remaining corners of the fan.

Step 8: Fold Net End Shut and Secure With Staples

With the netting securely attached to the fan, all there is left to do is close the open end of the netting.

First, pinch in the sides of the opening and press the whole opening down flat.

Next, fold the opening over itself a couple of times.

Finally, using a stapler, staple the folded end so it stays shut.

Step 9: Connect Fan to Power Supply

With the net complete, connect the fan to the power adapter cable, and connect the power adapter cable to the power supply. Plug the power supply into the wall to make sure the fan spins up and the LEDs light up.

Now you are ready to mount the trap!

Step 10: Position Finished Trap

Find a place to position the trap with a nearby power outlet. Since the fan is relatively lightweight, you can easily secure the trap to a spot with some string or a zip tie.

Step 11: Congratulations!

You've successfully built a mosquito killing machine!

Mosquitoes will begin to find their way into the trap once the sun is down and the lights are off. Inside the trap, the mosquitoes will die on their own after about a day.

Other than eventually emptying out the dead mosquitoes, there is no additional maintenance required.

The trap will continue to lure and trap mosquitoes as long as it is plugged in. If you decide to turn the fan off, I recommend crushing the end of the net to kill any surviving mosquitoes to prevent them from flying out of the trap.

Update: I added some pictures of my trap hung at the top my water closet. The trap is filled with the mosquitoes caught over the course of a month during Fall 2016.

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