How To: Make the Ultimate, Reusable Fruit Fly Trap

DIY Fruit Fly Trap
Learn how to get rid of fruit flies for good.

Ah … summertime. The pinnacle of the produce season means amazing things for your palate: sun-ripened fruit, homegrown vegetables, and fresh herbs for days.

Unfortunately, ripe produce also invites other guests to the flavor party: fruit flies. These little monsters (drosophilidae), with their big red eyes and kneejerk-wave inspiring flight patterns, aren't terribly harmful (they have a lifecycle of around ten days)…they're just really, really annoying. They tend to dig on ripe (or overripe) fruit, stale water, uncovered trashcans, etc.

But, even the cleanest homes can fall victim, especially those who buy organic-method or local farm raised produce, or have their own gardens and fruit trees. But, no worries, you can solve your fruit fly problem overnight, with about a minute of work and this DIY fruit fly trap.

Materials

  • One medium sized jar with lid – or – one drinking glass/bowl and some plastic wrap
  • Hammer and nail
  • 1/2 cup beer

Why do you need a fruit fly trap?

While fruit flies aren't particularly harmful, they are super annoying. Where do fruit flies come from? If you think they come from inside your fruit, you're mistaken. Fruit flies lay their eggs on moist surfaces, so nearly-ripe fruit is a perfect breeding group for their offspring. A fruit fly trap is the best way to keep these pesky insects from reproducing.

 

Is a fruit fly the same as a gnat?

Although both of these insects are in the same family, they're not the same species. Fruit flies are more likely to be found indoors, where they feed on fruits and vegetables. Gnats, on the other hand, are usually found outdoors, where they rotting organic matter and fungal growth.

 

1) Get A Jar or Glass Container for your Fruit Fly Trap

Since we wanted to use and reuse our trap all summer, we opted for a Mason jar. If you don't keep any on hand, any food jar will do, or you can use a drinking glass, and a piece of plastic wrap as the lid.

 

Fruit fly trap lid

2) Make Some Holes

Punch a series of holes in the lid using nail or awl. Make them big enough to allow the fly in, but not so big that it will be easy for them to escape.

 

Add beer to fruit fly trap liquid

3) Fill It With Beer Or Juice

Fill the container with about a half cup of beer, or to whatever fills the container halfway. If you'd rather not use beer, try using a fruit juice or apple cider vinegar flies love. 

Update: Adding a single drop of dishwashing liquid breaks the surface tension on the liquid, resulting in an immediate drown and no swarming around inside the trap. (Thanks, Mo!)

4) Place It Near The Flies

Screw on the lid, then take to the place where they flies are a-hovering…your fruit bowl, pantry, etc. Move any other sweet smelling things to a different location (like the refrigerator), making sure no fruit flies have hitched a ride.

 

Leave trap overnight

5) Wait

Overnight, the flies will smell the beer (or juice/vinegar), and eventually fly in to the fruit fly trap. They'll hover around above the liquid, eventually falling in and drowning. Every few days, pour out the flies and some of the liquid, and add more to give it a fresh aroma. Repeat as necessary.

Happy summer!

 

Update: it turns out that apple cider vinegar is actually a better liquid to use for this type of trap (it smells stronger and lasts longer than the beer … not to mention you don't have to waster perfectly good beer on fruit flies). Another fruit fly trap design involves using a paper cone to funnel the critters down into the liquid. 

You'll need a

  • A glass (I'm actually using an old pasta sauce jar)
  • A piece of paper.
  • Some slightly icky fruit or some apple juice to lure the unsuspecting little rotters

created on: 09/11/08

The picture is fairly self explanatory, you just roll the paper up, tape it and jam it up in top there. (I've taped mine down too).

But actually I reckon if you used fruit enough you could probably make the trap non-fatal. I was once in a Buddhist temple in japan, it was late September and the mosquitoes were enough to incite craziness. The monks told us NOT to swat them, we could shoo them if we must, but it would be better to let them have a meal then go on their way. I am not a very good Buddhist.