How to Make a Fly Trap From an Empty Soda Bottle

fly trap made from a soda bottle

The Spruce / Michelle Becker

The tried-and-true methods of ridding your indoors spaces of houseflies all have drawbacks. Flyswatters are messy and annoying to use, and pesticides run the risk of putting dangerous chemicals into the air. But an easy and inconspicuous way to rid your indoor space of flies is to set a simple trap made from an empty plastic soda bottle. Baited with some sweetened water or another attractive substance, a DIY fly trap set in a hidden area will lure ordinary houseflies like...well, like flies drawn to butter.

When to Trap Flies

You undoubtedly have noticed that there are certain times of year when flies are more prevalent. The time to set out your DIY fly trap is right when you start to see the first flies appear. In colder climates, this is often in the spring as the sun begins to warm the walls of the home, bringing out the first flies from their winter stupor. Houseflies have a predictable lifecycle that can include many hatch cycles each season, so if you set out your trap when the first flying pests appear, you stand a good chance at minimizing fly outbreaks, since you'll be trapping most of them before they have a chance to lay eggs that fuel the next cycle.

In some environments, trapping may be an almost constant affair. In warm climates near animal pens or pastures, for example, flies may be an almost constant presence, and you'll want to keep traps in place for most of the warmer months.

Project Metrics

 Working Time  1 hour
 Total Time  1 hour
 Material Cost  $0

What You'll Need

Equipment/Tools

  • Serrated knife
  • Permanent marker

Materials

  • Two-liter soda bottle
  • Piece of wire to hang your trap (optional)
materials for making a fly trap out of a soda bottle

The Spruce / Michelle Becker

Instructions

  1. Mark a Cutting Line

    Draw a line all the way around the bottle using a permanent marker, just below the tapered neck.

    drawing a cutting line on a soda bottle

    The Spruce / Michelle Becker

  2. Cut the Top off the Bottle

    Use a sharp knife with a serrated blade to cut along the line, severing the top of the bottle.

    cutting the top off of a soda bottle

    The Spruce / Michelle Becker

  3. Assemble the Fly Trap

    Remove the soda cap, then flip the top of the bottle upside down and slide it into the bottom of the bottle, like a funnel, to complete the fly trap.

    inverting the top of the soda bottle into the bottom

    The Spruce / Michelle Becker

  4. Bait the Trap

    Flies are attracted to nearly any decaying organic material, but it is meat and feces that they seek out to lay eggs, since the larvae (which we know as maggots) will immediately feed on those materials when they hatch from fly eggs.

    Few people, however, really want to bait an indoor trap with rotting meat or feces. A more pleasant choice is to place some slightly over-ripe fruit or other sweet substance into the trap. Even water saturated with some sugar, honey, or fruit-scented dish soap will draw flies. Flies seek out these materials to actively feed on, and they are easily trapped as they fly down the neck of the trap. If they get their wings wet, they are unable to fly. Want to get rid of wasps, too? This trap can serve a double purpose, as wasps are also drawn to sweets.

    To keep bees out of your trap, add a splash of vinegar to the mix.

    baiting the fly trap with fruit

    The Spruce / Michelle Becker

  5. Make a Handle for the Fly Trap

    If you prefer a hanging trap, use a hole punch to punch two holes at the top of the bottle. Make sure they go through both layers of the trap. Then thread a piece of wire through the holes, crimp the ends, and your trap is ready to hang.

    adding a handle to the fly trap

    The Spruce / Michelle Becker

How the Fly Trap Works

Flies smell the bait and fly into the bottle to get to it (either to lay eggs or to feed). Once inside they aren't able to navigate back up the narrow opening, and they become trapped.

To maintain the trap, empty the dead flies and re-bait your trap regularly. If you decide to use meat or animal droppings (chicken litter, rabbit pellets) as bait, you'll also need to destroy any larvae that you find in your trap. Rinsing the bottle out with hot water should do the trick.