DIY Mosquito Trap: How to Make a Homemade Trap (and What It Really Catches)

Quick answer

A DIY mosquito trap uses the same cue mosquitoes use to find you: carbon dioxide. The classic version is a 2-liter bottle with warm water, brown sugar and a little baker's yeast. As the yeast ferments the sugar it releases CO₂, and mosquitoes that follow it into the bottle's funnel can't easily find their way back out. Studies confirm that yeast-generated CO₂ does pull mosquitoes into traps, but the mix only gives off gas for roughly 12 to 27 hours in lab measurements, and it produces less CO₂ than the dry ice used in professional traps. So a bottle trap is a fun, cheap experiment that will catch some mosquitoes. It will not clear your yard. For real relief, pair it with weekly removal of standing water and set any trap away from where people sit.

Transparency note: we make Mosquito TNT, a ready-made CO₂ trap that works on the same principle as the DIY bottle. We've kept this guide honest about what the homemade version can and can't do, and we cite the research so you can check it yourself.

How a DIY Mosquito Trap Works

Female mosquitoes looking for a blood meal hunt in stages. From about 10 to 50 meters away, a mosquito picks up the plume of carbon dioxide you breathe out; only when it gets very close, under a meter, does body heat come into play (Caltech, on van Breugel et al., 2015, Current Biology). That long-range CO₂ cue is why professional surveillance traps use it: the CDC notes that dry ice in its traps releases carbon dioxide for exactly this reason (CDC).

A homemade trap swaps dry ice for fermentation. Yeast eats sugar and gives off CO₂, the same reaction that makes bread rise. The bottle's inverted top works as a funnel: it's easy to fly in and awkward to fly out. We explain the full hunting sequence, and why CO₂ matters more than color or scent, in our guide to mosquito traps compared.

How to Make a Yeast-and-Sugar Bottle Trap

This is the most widely shared recipe. The version below follows a homemade-trap sheet published by the City of Albany in Western Australia; a US Board of Health page (Town of Deerfield, Massachusetts) describes the same design.

What you need

• One empty 2-liter plastic bottle
• 1 cup of warm (not hot) water
• ¼ cup of brown sugar
• About 1 gram (a pinch, roughly ¼ teaspoon) of baker's yeast
• Black paper, black tape or an old dark sock
• Scissors or a craft knife, and tape

Step 1: Cut the bottle

Cut the bottle about a third of the way down from the top. Keep both pieces and remove the cap.

Step 2: Mix the bait

Dissolve the brown sugar in the warm water and let it cool to lukewarm. Water that's too hot kills yeast. Pour it into the bottom half of the bottle, then sprinkle the yeast on top. Don't stir: it will start fermenting on its own.

Step 3: Build the funnel

Flip the top section upside down and push it into the bottom half, spout pointing down, so it forms a funnel. Leave a gap between the spout and the liquid. Tape the two pieces together so there are no gaps around the edge.

Step 4: Make it dark

Wrap the bottle in black paper or tape, or slide it into a dark sock, leaving the funnel opening clear. Mosquitoes' eyesight is poor, and dark, high-contrast shapes stand out to them (more on that in what colors mosquitoes hate).

Step 5: Place it and refresh it

Set the trap in a shady spot away from where people sit (see placement below). Council sheets suggest changing the mix every two weeks, but lab measurements show fermentation gives off CO₂ for only about half a day to a little over a day, strongest early on. For best results, refresh the mix every day or two.

What the Research Says About Homemade CO₂ Traps

This isn't just a viral hack; scientists have tested yeast-and-sugar CO₂ as a cheap substitute for dry ice. The short version: it works as a CO₂ source, but it's weaker and shorter-lived than the professional options.

Notice what these studies measured: whether the CO₂ helps a trap catch mosquitoes. None of them tested whether a bottle trap in a backyard reduces bites. That's a different, harder question.

Why a Bottle Trap Won't Clear Your Yard

The CO₂ runs out fast

A trap only works while it's putting out CO₂. If your mix peaks in the first few hours and fades within a day, a bottle left out for a week is mostly just a bottle of sugar water.

Even commercial traps rarely stop bites on their own

The University of Wisconsin–Madison's entomology department is blunt: traps bought by individual homeowners "usually do not work to reduce human biting" (UW–Madison). The reason is numbers. Mosquitoes can go from egg to adult in 7 to 10 days, and most of the ones biting you were born close by, as we explain in our guide to mosquito-proofing your yard.

A badly placed trap can make things worse

The American Mosquito Control Association warns that traps "may actually draw more mosquitoes into an area than they can possibly catch" (AMCA). Put a CO₂ source right next to your patio chairs and you may be inviting mosquitoes to the very spot you want to protect.

Where to Put a DIY Mosquito Trap

A USDA researcher quoted by the University of Florida gave the key rule: keep the trap out of the immediate area where people gather. In practice:

• Away from seating. Put it on the far side of the yard, not beside the grill or the patio table.
• Between you and the source. Aim for the side where mosquitoes come from, such as shrubs, shady corners or a wet low spot, so they meet the trap before they meet you.
• In the shade. Many backyard mosquitoes rest in shady, humid vegetation during the day, and heat can cook the yeast mix.
• At the right time. Set it out before peak biting hours, which for many species are dawn and dusk. See when mosquitoes are most active.

Other DIY Mosquito Traps: What Works and What Doesn't

The bottle trap isn't the only homemade design online. Here's how the common alternatives stack up against the evidence:

If you try a DIY egg-laying bucket, treat the water with Bti, a bacterial larvicide. The EPA says Bti "has no toxicity to people" and affects only the larvae of mosquitoes, black flies and fungus gnats (EPA). Without it, an untended bucket is simply a mosquito nursery. Our guide to mosquito larvae covers what to look for.

The Mistake That Turns a Trap Into a Mosquito Nursery

Every water-based DIY trap has the same weakness: it's standing water. The CDC's advice for any container at home is to empty and scrub, turn over, cover or throw out items that hold water once a week. Apply that to your trap too: dump and refill it at least weekly, and never pour old trap liquid into a flowerbed saucer or gutter where it can collect. For the full checklist of breeding spots around a home, see where mosquitoes lay their eggs.

DIY Bottle Trap vs. a Ready-Made CO₂ Trap

Here's an honest side-by-side. (We make Mosquito TNT, so weigh our view accordingly.)

The principle is the same across all three: CO₂ is the cue mosquitoes use to find a host. What changes is how long and how steadily the CO₂ keeps coming. If you like the idea of the bottle trap but don't want to remix it every other day, Mosquito TNT 2.0 is our take on a longer-lasting, no-electricity version. For a wider comparison, see our best mosquito traps for the yard roundup, and skip the UV zapper, which kills mostly other insects (do bug zappers work on mosquitoes).

A DIY Plan That Actually Reduces Bites

If you want to go the do-it-yourself route, the trap should be the last layer, not the first:

1. Remove breeding water weekly. Saucers, buckets, toys, tarps and clogged gutters. This matters more than any trap.
2. Protect your skin at peak hours with an EPA-registered repellent; homemade sprays don't last (see how to make mosquito spray at home).
3. Keep mosquitoes out of the house with intact screens and closed doors (see getting rid of mosquitoes in your room at night).
4. Run a CO₂ trap away from seating, refreshed on schedule, to keep catching host-seeking females through the season.

Frequently asked questions

Do homemade mosquito traps work?

Partly. Yeast-and-sugar bottle traps release carbon dioxide, and studies show yeast-generated CO₂ does help traps catch mosquitoes. But the gas output is weak and lasts only about 12 to 27 hours per batch, and even commercial traps rarely reduce bites on their own. Expect to catch some mosquitoes, not to clear your yard.

How long does a yeast mosquito trap last?

In lab measurements, a yeast-and-sugar mix gave off CO₂ for at least 12 hours in one study and at least 27 hours in another, strongest early on. Advice to change it every two weeks isn't backed by measurements, so refresh the mix every day or two for best results, and empty the bottle at least weekly.

What is the best bait for a homemade mosquito trap?

Carbon dioxide, because it's the main long-range cue mosquitoes use to find people. At home, fermenting yeast and sugar is the easiest steady source. In studies, dry ice produced more CO₂ and caught more mosquitoes, but it's impractical for most households.

Can you make a mosquito trap with baking soda and vinegar?

The reaction does release CO₂, and UF/IFAS researchers have noted that carbonates such as baking soda combined with weak acids such as vinegar produce it. A simple kitchen pour isn't a controlled source, though; researchers needed a purpose-built system to keep CO₂ flowing for about 10 hours.

Where should I put a mosquito trap?

Away from where people gather, ideally between your seating area and the shady, wet spots mosquitoes come from. A CO₂ trap placed right beside you can draw more mosquitoes to that spot than it catches.

Can a DIY mosquito trap make the problem worse?

It can in two ways. A trap placed next to your seating can bring mosquitoes closer to you, and any trap that holds water can become a breeding site if you don't empty it. Place traps away from people and dump and refill them at least once a week.

Sources

• Caltech (2015). "Mosquitoes use smell to see their hosts" (on van Breugel et al., Current Biology). caltech.edu
• CDC, "Mosquito Surveillance Traps." cdc.gov
• CDC, "Mosquito Control at Home." cdc.gov
• City of Albany (2016). "Homemade Mosquito Trap." albany.wa.gov.au
• Town of Deerfield, MA, Board of Health. "Instructions for a Homemade Mosquito Trap." deerfieldma.us
• Saitoh, Y. et al. (2004). Journal of the American Mosquito Control Association 20:261–264. PubMed
• Sukumaran, D. et al. (2016). Parasitology Research 115:1453–1462. PubMed
• Harwood, J.F. et al. (2014). Journal of the American Mosquito Control Association 30:275–283. PubMed
• Oli, K., Jeffery, J. & Vythilingam, I. (2005). Tropical Biomedicine 22:249–251. PubMed
• University of Wisconsin–Madison, Department of Entomology. "Carbon dioxide-baited mosquito traps." wisc.edu
• American Mosquito Control Association. "Traps." mosquito.org
• University of Florida News (2005). "Carbon dioxide mosquito traps no magic bullet, say UF experts." ufl.edu
• ScienceDaily (2015), on UF/IFAS research into carbonate-based CO₂ sources. sciencedaily.com
• Hong et al. (2025). Insects. PMC
• Barrera, R. et al. (2014). Journal of Medical Entomology 51(1):145. oup.com
• U.S. EPA, "Bti for Mosquito Control." epa.gov