The Bottle Funnel Trap

By the Fruit-Flies.com editorial team · Updated July 2026

Take an empty plastic bottle, cut off the top, flip it upside down into the base, and you have built the sturdiest one-way fruit fly trap there is — no cling film, no elastic bands, and it stands up on its own for weeks. The funnel guides flies down toward the bait and makes the exit almost impossible to find. Here is how to cut it, what to bait it with, and how to get several uses out of a single bottle.

Why a funnel beats an open dish

The genius of this design is geometry. An inverted bottle neck is a wide entrance narrowing to a small opening pointed down at the bait. A fruit fly follows the fermentation smell down the smooth plastic slope and through the small hole with ease. But when it tries to leave, it flies up and out toward the light at the shoulders of the bottle — away from the narrow neck hole, which now sits in the middle surrounded by sloping plastic. It rarely stumbles back through. This is the same one-way logic as a pinholed plastic wrap jar trap, but a rigid funnel is more forgiving, more durable, and stands up to a knock without collapsing.

How to cut and build it

1. Rinse an empty bottle. A clear 500 ml or 1-litre drinks bottle is ideal — clear plastic lets you see the catch and lets light in to confuse escaping flies. Peel off the label and remove the cap entirely.
2. Cut off the top third. Slice cleanly around the bottle where the straight sides begin to curve up toward the neck — roughly the top quarter to third. You now have two pieces: a tall base cup and a funnel-shaped top.
3. Add the bait to the base. Pour 2–4 cm of your chosen lure into the base cup (bait options below). Leave a good gap between the liquid and the funnel tip so flies have room to enter.
4. Invert the top into the base. Turn the cut-off top upside down — neck pointing down — and nestle it into the base so it sits like a funnel over the bait. The cut edges should meet neatly.
5. Seal the seam. Run a strip of tape around the join, or fold the edges together, so flies can't sneak in or out at the rim. The only way in should be the funnel hole.
6. Place and monitor. Set it where the flies gather and leave it. Because it's enclosed and stable, it can run for days with minimal fuss.

Which bait to use

The funnel is just the delivery mechanism; the bait does the attracting. Match it to what you have on hand:

A splash of vinegar with a piece of rotting fruit dropped in is hard to beat inside a funnel trap, because the enclosed space concentrates the smell. Each of these has its own full write-up: the apple cider vinegar trap, the wine, beer and yeast trap, and the rotten fruit trap. For a ranked overview, see the best bait for fruit flies.

Reusing the bottle

One of the quiet advantages of this trap is longevity. When the catch slows or the bait goes stale, you don't have to bin the whole thing:

• Lift out the funnel, tip the old bait and flies into a sealed bag, and rinse both halves.
• Refill with fresh bait and reassemble — good for another few days.
• After several rounds, or once the plastic gets grimy, recycle the bottle and start with a new one.

Because it's built from a bottle destined for recycling anyway, it costs nothing. Just be aware that empty bottles and cans are themselves a common fruit fly magnet — the sugary film inside a "rinsed" bottle is a breeding site. If your recycling attracts flies, read recycling and empty bottles.

Getting the most from it

A few refinements sharpen the catch. Keep the funnel tip a couple of centimetres above the liquid so flies can move around inside rather than immediately hitting the surface. Use clear plastic so the interior stays bright and confuses flies trying to escape. And add a drop of dish soap to any liquid bait so that flies which do land on it sink instead of resting and eventually escaping — the surface-tension trick explained in the dish soap method. If your funnel trap is underperforming, our diagnostic on why your trap isn't working walks through each fix.

Where to put it

Set the bottle trap on the counter beside the fruit bowl, next to the bin, or wherever the swarm is densest — it needs to sit on the flies' flight path to compete with real food sources. Its stable, weighted base makes it a good pick for busy spots where an open dish would get knocked over. For a serious infestation, run two or three around the kitchen. Our guide to where to place fruit fly traps pinpoints the best locations.

Don't forget the breeding source

However many flies a funnel trap catches, it only removes the adults out flying today. Fresh flies keep emerging from eggs hidden in drains, spills, damp cloths, or the fruit bowl, so the trap has to run alongside a real clean-up to actually end the problem. Find what they're breeding in with how to find the breeding source, then follow the five-day fruit fly plan. Compare every trap style at the traps hub, and tie the whole approach together at the main remove fruit flies guide.