Plastic Bottle Mosquito Trap




About: Hi everybody! I'm Filippo from Bologna, Italy! My friends call me Orso (Bear) :) I follow Instructables since 2009, and it has always been one of my favourite websites. I've bulit a lot of fantastic things t...


Hello dear friends!

As some of my followers already know, I live in Bologna (Italy), in the heart of Po river Valley.

This area is known as the wettest one of Italy. This is due to terrain, level (a lot of areas are UNDER sea level) and weather.

These factors result in very hot temperatures in summer, very cold ones in winter, an incredibly thick fog but, mostly, giant and aggressive mosquitoes.

There is a city, Comacchio (only 55 miles from Bologna), that is known as the "Mosquitoes Town". XD

Obviously is nothing tropical, but it's very annoying!

It's really difficult to enjoy summer evenings without using pesticides, sprays or other stinky poisons. Or, you can always avoid using anything and... be eaten alive by these little vampires.

While mosquitoes are useful for the ecosystem (did you know that mosquitoes are the main cocoa plants pollinators? No mosquitoes means no chocolate!!!), we don't want them to fly around our garden and bite everything that's alive, pets included.

In this Instructable, I want to show you an all natural and potentially free way to create an efficent mosquito trap with little more than a plastic bottle!

Why potentially free? Because we will use materials that are always present in our home!


Let's start with our shopping list.

Step 1: Shopping List

For our trap we will need:

  • Plastic bottle (2 liters one is good)
  • 4 spoons of white sugar
  • 10gr (0.70oz) Brewer's yeast (freeze-dried one or fresh)
  • 200ml (6.75oz) water (and a pot for boiling)
  • Tape
  • Black cardboard (or similar dark covering)
  • Scissors

Optional for hanging

  • String
  • Liquor can container (like Baileys one, look at the images for more info)
  • Drill

If you have the liquor can container, you won't need black cardboard, we will see why.

NOTE: A lot of users reported me different results. Someone have found a full trap and some other an empty bottle after several attempts. You should experiment a bit by changing the amount of yeast in each traps, in fact only some kind of mosquitoes are attracted by this trap and the amount of CO2 released change the effectiveness depending on climate/humidity of your zone. For example, I've found a full bottle on the first attempt and much less dead mosquitoes in the next two bottles (with same recipe). I'm experimenting different mixtures in these days ;)

As you can see, these are very common and easy to find materials.

I didn't have to buy anything except for the brewer's yeast (I can't find fresh one...darn).

Let's move on the first thing: cutting the bottle!

Step 2: Prepare Your Bottle

The first thing to do is cutting your bottle at the right height.

You have to cut 2-3 cm (about 1 inches) over the point where the bottle becomes thinner (the grip).

Use your scissors for that, or a Dremel if you have one! :)

You don't need to be super precise, but try to make a straight cut.

Now you have 2 separated pieces.

Easy, isn't it? :)

To the mixture!

Step 3: Mixture

Now, put 200ml (6.75 oz) of tap water in a pot and boil it for 10 minutes.

This will eliminate the possible presence of chlorine.

Don't boil more thank 10 minutes, or too much water will evaporate.

While water is still hot, add 4 spoons of white sugar and mix until everything will be dissolved.

Now wait until water is at room temperature.

It's important, or high temperatures will kill the yeast and deform the plastic bottle.

Then, pour the sweety mixture in to the big part of the bottle (obviously).

Finally, add the brewer's yeast.

Don't mix yeast! If you do so, the reaction that attracts mosquitoes will NOT last longer.

Now that the mixture is ready, put the top part of the bottle inside the big one, face down, to create a funnel (the picture shows it well).

Finally, close the border with some tape to fix it up and make te cap hole the only way in-out for mosquitoes.

I've used black tape for electrical work, it's good for this kind of fixing.

Step 4: Prepare for Hanging

This step is optional, but I highly recommend it.

You can finish now your trap by wrapping the bottle with black cardboard to add a sun protection (not from the heat but from UV).

But, if you want a more stylish solution, I suggest the use of a liquor can container (the Baileys one is very popular).

Use a drill to open two holes near the top of the can, in opposite directions.

This holes will be used to create a knot with some string and use this can as a "hanging bottle container".

You will have a easy and quick way to change bottles without the need to take them down from hanging every time!

A bottle case ;)

Plus, this covering will protect the bottles from UV sun rays.

Finally, you won't have to make holes on the bottle surface, making some precious CO2 to go outside (next step to discover why!)

Step 5: Ready for the Hunt!

Now make a knot in the other hole of the can and hang your trap outside!

In your garden or in your balcony, the best place is a dark and humid one, not exposed to direct sunlight.

But, how does it work?

The brewer's yeast produce a small but continue amount of CO2, that, mixed with the high sugar amount in water, creates a smell that is irresistible for mosquitoes!

So, these little devils fly inside the small hole of the bottle cap and get stuck, with no way out except for the hole itself. The percentage of mosquitoes that fly out again from the trap is ridiculously low.

The cover (black cardboard or the can) prevents UV rays from killing yeast and stopping CO2 production.

Also, we use tape around corners to prevent CO2 from going out from the bottle in "high" quantities.

The amount of yeast (10gr) last for about 2 weeks.

After this time, you will have a bottle full of mosquitoes! :D

You can clean it and fill it with new mixture, or prepare a completely new one.

With the quick change hanging system, it will be easy to have a new trap in minutes! :D

You now have a 100% natural and green trap, with zero amount of poisons or other harmful chemicals!

Hope you'll like and help you from getting bit ;)

From Italy, this is Filippo

Ciao a tutti!

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Epilog Challenge VI

Participated in the
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7 People Made This Project!


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431 Discussions


Question 1 year ago on Step 5

I assume you are installing the bottle cap back on the bottle (funnel), what size hole are you drilling in the cap?


1 year ago

Same mixture and construction to catch the dreaded Yellow Fly, only I add 2 egg whites. Seems to work real well as well as with mosquitoes, sand fleas, yellow jackets and fruit flies along with other critters I can't identify. Just huge black globs. I had to empty 1 trap 3 times in 1 week. I now have 4 working. Will see how often I have to empty them. I just dump them in my compost bins.


1 year ago

Grazie Filippo, proprio in questi giorni pensavo a costruire una soluzione fai da te come quella che hai proposto. Ora posso eseguirla passo passo!


Question 1 year ago on Step 5

Like your project. Will try it. Question: you said the mixture lasts about two weeks. What do you do with the trappings? Clean it out and start all over? Are the mosquitoes dead?

Thank you in advance for your response.

Regards, Jimbo

1 answer

Answer 1 year ago

You will want to throw it away. It'll be pretty disgusting... There might be a few still alive.

spark master

1 year ago

EEAK, my favorite thing is pollinated by that which I hate the most!!!!


1) if you let water sit for couple of hours in the sun it will dechlorinate , or use water through a carbon filter, or just use rain water.

2) make an Ovi-trap then loose the yeast and just use rain water and a few grass clippings left to rot in it

Make a lot of ovitraps. Ovitraps do not kill the mommie skeeters, (who are the biters), they lay eggs on it then the larva fall in are trapped and drown or starve to death. Either way we win.

And get all your friends to make a few put them all over the garden, under bushes They do not need to be big , just properly made and refilled if heat dries them up.

Skeeters do NOT like chlorinated water so rain water is fine water set out for a day will be good enough. Drop in a few grass clippings and they will rot. Skeeters love it

your trap with a good splash of beer will attract wasps/yellow jackets, and they can escape either!

win win win



2 years ago

just a thought on making it easier to empty / clean (haven't read all the comments so I'm not sure if someone else has said similar) if you have two bottles, cut the bottom of the first one, screw on lid, mount upside down, use the top section of the second bottle as the funnel as per the instructable. to empty just open the lid / sump cap and pour down the drain.

3 replies

Reply 2 years ago

A further thought, though not as green, is to line the bottle, or maybe even replace the bottle, with a used plastic bag? Then you could dispose of the messy contents and replace with a new bag & mixture.


1 year ago

Hi! I really want to do this but I need the alive ones for research purposes. How can I keep them using this without actually killing them?

2 replies

Reply 1 year ago

Just collect them before they die.
This will not kill them, just contain them.

Well, until they die of starvation...


Reply 1 year ago

You could add a mesh screen halfway the bottle to keep them from drowning in the liquid, but you'd need to "harvest" them in time to keep them from starving, I guess.


1 year ago

Lots of mosquitoes in Wisconsin and I can't wait to try this and see how it works. Th


2 years ago

Bravo e grazie mille per questo. As someone married to a Ugandan with family in East Africa, where malaria is extremely prevalent, this idea is perfect. I am not sure how hard it is to find brewers yeast there but all the other materials are readily available. Anything to combat malaria would be beneficial. Thanks again for the contribution and in terms of the contests you entered, in bocca al lupo!

2 replies

I am sorry pseudo science banned DDT world wide. That little thing accounts for 1 million unnecessary deaths per year in Africa due to malaria.


Reply 2 years ago

Hi Cam. East Africa is home to the best, traditional home-brewed beer. So, you can imagine the land has never suffered a yeast supply shortage since the beginning of time.


2 years ago

Hi, I don't have any sugar in the house. Do you think honey would work as an alternative?

2 replies

Reply 1 year ago

Sugar is sugar. Sugar, molasses, honey, agave nectar, corn syrup, etc. are all sugar.


Reply 2 years ago

I could just prick my finger and squeeze the blood into the bottle - they seem to love that.