But an easy and inconspicuous way to keep flies from buzzing around inside of your home 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 quickly lure ordinary houseflies. Flies smell the bait and fly into the bottle to get to it (either to lay eggs or to feed). Once inside, they are easily trapped as they fly down the neck of the trap. Flies will become trapped because they can't navigate back up the narrow opening or they will be unable to fly if their wings get wet. This trap can be used indoors or outdoors.
Equipment / Tools
- Serrated knife
- Permanent marker
- Cutting board
- Hole punch (optional)
- Two-liter soda bottle
- Bait, such as ripe fruit
- Vinegar (optional)
- Piece of wire to hang your trap (optional)
Mark a Cutting Line
Draw a line all the way around the bottle using a permanent marker, just below the tapered neck.
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. Cut on a cutting board so there's no damage to your counter or table surface.
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.
Bait the Trap
Remove the "funnel" from the bottle so you can place the bait. Choose a bait for your trap.
Flies are attracted to nearly any decaying organic material. Though it is meat and feces that flies seek out to lay eggs (the larvae, which we know as maggots, will immediately feed on those materials when they hatch from fly eggs), few people will want to use that as indoor bait. Consider these pleasant ideas for bait:
- Slightly over-ripe fruit
- A 50/50 water and sugar mix
- Water mixed with honey or maple syrup for a stickier solution
- Fruit-scented dish soap
If you are using this trap outdoors, use a more pungent bait. To keep bees out of your indoor or outdoor trap, add a splash of vinegar to the mix.
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.
Tips to Make the Fly Trap Work
You undoubtedly have noticed that there are certain times of year when flies are more prevalent. 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 the fly traps in place for most of the warmer months.
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, or just create a fresh new trap.
Nicolopoulou-Stamati P, Maipas S, Kotampasi C, Stamatis P, Hens L. Chemical pesticides and human health: the urgent need for a new concept in agriculture. Front Public Health. 2016;4. doi:10.3389/fpubh.2016.00148
Merchant, Michael. Indoor Flies and Their Control - What Causes Indoor Flies?. Texas A&M Agrilife Extension Service.