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!

<p>Love the idea but sadly only found this Ible at the end of summer...<br>Have to try it next time I manage to go fishing though.<br><br>A thing about the yeast:<br>Dry yeast requires luke warm water to &quot;activate&quot; the cells, in cold water it takes really long and too hot water will damage the cultures.<br>Apart from the water yeast also needs something to eat, here in AU we can get Vegemite, it is based on dead yeast as the main ingredient.<br>A tiny bit of this and half a teaspoon of sugar will make the yeast very happy and productive.<br>A byprodut is alcohol and once the concentration is too high the yeast dies off and the fermentation stops.<br>This takes about two to three weeks depending on temperatures.<br>Good thing about yeast is that always new cells are produced and some of them tolerate heat and higher alcohol levels better.<br>So if you would add a tap or clamped rubber hose youcould partially empty the trap and just fill up again with a mix of water and sugar.<br>This way the same trap can be used throughout the entire summer.</p>
<p>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.</p>
That's a clever idea, thanks!
<p>Hi, I don't have any sugar in the house. Do you think honey would work as an alternative?</p>
&quot;add brewers yeast&quot; and how much is that?
<p>The sugar is basically food for the yeast. Dump the whole packet in if you want, and then maybe if you're curious, make a couple more and try adding half to each. Maybe experiment with different concentrations if you want, but leave the sugar concentration as is. Too much will inhibit growth of the yeast due to osmotic pressures being too high. Basically, they use the energy from sugar in cellular respiration, where oxygen is the terminal electron acceptor and CO2 is a byproduct. The CO2 is what attracts the mosquitoes. If the yeast run out of oxygen, they can no longer respire and will begin the process of alcohol fermentation. YUM! SKEETER BOOZE!!!</p>
Grazie Phi
<p>In a pinch, since I cannot go out right now and buy brewer's yeast or any yeast, can I use bread?</p>
<p>I have seen this mosquito trap in many web pages, but still nobody with good results. I have tried many times with different proportions and procedures but no results. Can anyboy confirm any good result? Thanks.</p>
<p>I looked and did not see it mentioned so.</p><p>Some bugs are attracted to carbon dioxide which is what animals breath out.</p><p>This is how they are able to find their prey.</p><p>So the CO2 simple tells them that an animal is nearby and in they go.</p><p>Just thought some might not know this and want to know why it attracts them.</p><p>Hope this helps :)</p>
So .. that's why my first try in doing this didn't work. (The instruction is not from you). The water should be boiled and the yeast added while the water is still warm. I will make another mixture. Thank you!!
<p>Mosquito kill! Listerine,the yellow stuff. Spray lawn and it will kill on contact and kill those that land. Lasts for hours, We are able to sit out all afternoon and evening.</p>
<p>fantastic idea and green too!:)</p>
Bravissimo saluti de la Argentina. It's so easy to do and Work's perfectly. Thanks!!!! All my points 4 U today
<p>These soda bottle flying insect traps (mosquito, fly wasp, etc.) don't work worth a darn, but somehow they keep getting plastered all over the Internet as the best thing since baked bread.</p><p>Don't waste your time.</p>
<p>Hi, made my bottle mosquito trap... just one trapped but I think it&acute;s because I didn&acute;t mix everything right. Will try again tonight.</p><p>Thanks for the instructable. Very nice. Hello from Colombia by the way.</p>
<p>Cool! Thanks Filippo.</p>
<p>Hey... You can do one thing: add a tube going through your window... With a cork on the end of the tube or something of course... so... the yeast runs out and the chemical reactions stops, then just put more yeast through the tube. If you want to get fancy, then you can coat the inside of the tube with some sorta bug killing spray, or maybe some weak glue, as mosquitos have very weak flying power... then, you can just keep the system running, which might last like 5/6 times, then you would have to kill the mosquitos inside the bottle and clean the tube out from dead mosquitos...</p>
<p>As the yeast consume the sugar, they convert it into alcohol (you could view it like this - they eat sugar water, and piss alcohol and fart CO2). One reason the yeast stop reproducing (and the colony dies) is the alcohol content gets too high and it becomes toxic. Thus, you could not add more yeast - there is a reason they stopped reproducing. ;)</p>
whups... I guess if someone is REALLY lazy to go outside and clean out the trap once in a while, they can have a system where the alcohol dumps out and water floods in as yeast dumps in again... But, I thought of a greater idea: Make a large container, maybe a fish aquarium, then do the same thing, except with 3/4 holes... More intake, and more storage... but honestly, you can put sugar and water, a few drops of any color food coloring, but not yellow cuz yellow repels flies, and then once the sugar ferments, you get like instant flies, as soon as you open it... if each of the holes are small enough, then it should work... One downside: maggots. UGH I tried this trap with a soda bottle... with sugar and a few pieces of meat... The flies swarmed into the trap, I forgot to empty it, then in the morning, I see maggots squirming around... Somehow, the bottle tipped over and... oops! I created more flies instead of trapping more...
<p>The reason for some traps not working is that the bottle has become filled with pure CO2, which would be fatal for mosquitoes. There needs to be some air exchange. Changing the funnel to mosquito netting would allow the CO2 to escape without becoming concentrated. </p>
<p>And there's a problem with the mosquitoes being killed instead of trapped ? ;-)</p><p>Wouldn't mosquito netting keep the mosquitoes from getting into the trap ? What am I missing from your suggestions ?</p>
<p>The mosquitoes won't enter the trap if it is a fatal atmosphere. They just follow small concentrations of CO2. The netting is a cone with a ~1/2&quot; hole in the bottom/center. The mosquitoes will crawl/fly toward the increasing CO2, and go through the hole, and are trapped.</p>
<p>Ah, a mosquito netting<strong> funnel</strong>, now I get it, missed the intent originally. That sounds well reasoned out. Thanks for the followup elaboration, appreciate it !</p>
<p>Thanks for the good directions about boiling the water and protecting the trap from UV light.</p>
<p>Fabulous. The darker colour around the trap also encourages mosquitoes to hide there at dawn. They prefer darker areas and even darker clothes on their dinner.</p>
<p>This is a very good method to trap Mosquitos naturally. We in Puerto Rico are being threatened by the sam Aedes Aegypti that carries Chikungunya and now Zika. I will forward this to all my friends and family so they can build this simple trap. Thank you!</p>
<p>People carry Zika and infect others in much the same way as mosquitos do. LOL I wonder if they can be trapped as well. </p>
<p>Huh... Unless 69 happens, or blood to blood contact occurs, the zika cannot be spread human to human. Or possible saliva... Mosquitos spread zika by drinking zika infected blood, then the virus takes over in their organ that creates the numbing substance, that makes you not feel pain when a mosquito bites, then the mosquito goes to another human and injects the numbing substance- now infected with zika- into another human, and that happens over and over. Mosquitos spread the virus through organisms in the <em>mammalia</em> class. Or- mosquitos can just go berserk and bite each other... Which is unlikely, so ArtS13, humans cannot spread viruses in the same way mosquitos do... Please don't argue back because that makes this long comment worthless then. </p>
<p>BrianM172</p><p>Nice post but I encourage you to please check your sources. A quote from the CDC website updated March 8, 2016</p>&quot;What we know<ul><br><li><strong>Zika virus can be spread by a man to his sex partners</strong>.<li>In known cases of likely sexual transmission, the men had Zika symptoms. But the virus can be spread before, during, and after men have symptoms.<li>The virus can be present in semen longer than in blood.</ul><p>If you have vaginal, anal, or oral (mouth-to-penis) sex, <a href="http://www.cdc.gov/condomeffectiveness/male-condom-use.html" rel="nofollow">use a condom the right way, every time</a>.&quot;</p><p><a href="http://www.cdc.gov/zika/transmission/sexual-transmission.html" rel="nofollow">http://www.cdc.gov/zika/transmission/sexual-transm...</a></p><p>Thank you and have a great day!</p>
<p>I am definitely going to make this, Mosquitoes should be considered our state bird In Wisconsin, (USA). This is brilliant, thanks for the info!</p>
Grazie per aver condivizo questa idea. Saluti da Argentina!
<p>Does sea level have any affect on this that you know of?</p>
<p>I don't think sea level will make any difference. While mosquitoes have a low ceiling for their flight and lifestyle, typically below 3000 feet above sea level, if you need a mosquito trap, this will work wherever you are. The yeast doesn't care, and if you have high-flying mosquitoes it will probably still work on them.</p>
<p>I live just East of the Cascades in Central Oregon. The lowest elevation here is 3500 ft MSL. Mosquitoes are prevalent here all the way up to well over 5000 ft. so your 3000 ft limitation if it's real must only apply to a specific mosquito - they are all over the place including up in the mountains well above 3000 ft.</p>
<p>I live in Canada where the mosquitos have horns and can carry live beavers and small cats away.....we use fires and lots of smoke to repel the little buggers but they are not as bad a no-seeums or deer flies or black flies for that matter. It seems that they like a particular blood group plus if you have eaten red meat they like you more. My mother-in-law is Italian and the mosquitos love her which is great 'cos they stay away from us. So the bottom line is marry an Italian and invite the mother-in-law to all your barbeques........but seriously, I haven't tried the CO2 with brewers yeast, I will try and let you know at the end of summer. Cheers</p>
<p>Thanks for the laugh Ridgepg. I'm familiar with all those pests you mentioned. </p><p>I use Basic H ( Google it! ) as a repellent. Works great, is non toxic and you can apply it to your pets and kids too.</p>
Or be an italian male with 90 % body hair covering his body. The only places i get bitten is on the knuckles, elbows and knee caps !lol
<p>Thank you, Fillippo! I have another low tech suggestion for those with an electrical outlet nearby: simply use a fan. Mosquitoes are weak fliers and can't fly into even a gentle breeze generated by an electric fan. Stay cooler and bug-free at the same time!</p>
Is this really true ? I do hope it is ! Cheers for spreading the knowledge.
<p>Yup! Straight from the American Mosquito Control Association's website.</p>
<p>I am living ONE kilometer from the Po river, in the Parma region ! I'm pretty sure I have EVEN MORE mosquitoes than you do ! :-)<br>We use a bottled gas device that we rent every summer that also attracts mosquitoes thanks to CO2 but it also releases pheromones that attracts female mosquitoes in order to decrease the global population. It doesn't attract other insects (butterflies, etc) which is nice and has no chemicals that kill the insects. It just attracts them thanks to the hormones and captures them in a net so that they can't get out anymore. Works quite well but of course you can never get rid of the billions of mosquitoes around. and it's quite expensive... so I'll give your trap a try !</p>
<p>Male mosquitoes do not bite animals. They live on plant juices. As soon as the females mate, their fertilized eggs need blood of animals to grow. This makes the female mosquitoes blood-thirsty. Male mosquitoes always stay outdoors except while mating. The mating takes place usually during the sunrise or the sunset hours. If you can trap the mosquitoes during these hours outside the house with UV light traps, you can considerably reduce the number of mosquitoes biting you. This CO2 trap can be used along with the UV light trap where the mosquitoes congregate for mating. The life cycle of mosquitoes itself is very short. The female mosquitoes have to drink blood and make a fast exit to lay their eggs. Otherwise, they will die.</p>
<p>Male mosquitoes do not bite animals. They live on plant juices. As soon as the females mate, their fertilized eggs need blood of animals to grow. This makes the female mosquitoes blood-thirsty. Male mosquitoes always stay outdoors except while mating. The mating takes place usually during the sunrise or the sunset hours. If you can trap the mosquitoes during these hours outside the house with UV light traps, you can considerably reduce the number of mosquitoes biting you. This CO2 trap can be used along with the UV light trap where the mosquitoes congregate for mating. The life cycle of mosquitoes itself is very short. The female mosquitoes have to drink blood and make a fast exit to lay their eggs. Otherwise, they will die.</p>
<p>Most of this kind of experiment need a vid in order to see the final results and the mosquitoes trapped inside trying to go out from the trap also . To see and believe ;) Thanks</p>
<p>Sorry to be the devil's advocate. There is one single problem related to this trap: it does attract mosquitoes to the near vicinity. Therefore, any other possible water accumulation near to the trap will definitely create more mosquitoes in places where there is no trap... It is a risky solution; down here in Brazil, due to the Aedes egipty infestation, it is not recommended. But otherwise an intelligent trap in itself!</p>
<p>Like it, and will make one for the summer, hopefully stop those little critters.</p><p> Thanks</p>
There are two types of mosquitoes. Those that feed off animals and those that live off plants. Plants give off co2 remember. So I'm not sure if this is attracting the right kind of mosquito or not. Probably not.
<p>Well &quot;Dr&quot; Will---Obviously you don't understand plant physiology OR mammalian physiology. Plants TAKE IN CO2,and GIVE OFF O2. An animal TAKES IN O2 and GIVES OFF CO2. And there are FAR more than two types of mosquitoes. Since CO2 is one factor that mosquitoes use to find victims, this trap has a reasonable chance of attracting them.</p>

About This Instructable




Bio: 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 ... More »
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