The Great Fruit Fly Invasion

Back in 1984, I did some basic genetics research on drosophila melanogaster, aka fruit fly. Fruit FlyMostly this involved looking at them under a microscope while they were anaesthetized with ether and breeding them in different combinations to see how various characteristics got passed down to children.

I though it was all innocent enough — they were just fruit flies. Obviously I was wrong, as this year the fruit flies have finally gotten around to exacting their revenge by reproducing in great numbers and spreading their armies throughout Charlottetown.

This summer you cannot mention the species in this city without sighs of tired resignation from all around. The fruit flies have taken over, and there doesn’t appear to be anything we can do about it.

Catherine has tried these gizmos from Lee Valley Tools. They work, but they simply can’t keep up with the exploding population.

No matter of cleaning, putting everything remotely attractive to fruit flies in the fridge or in sealed canisters, or any other maneuver we’ve taken has had any effect at all.

Much of the problem extends, no doubt, from the hundreds of these compost containers that now populate the city. Alas the Island Waste Management System has a waste video game, but no advice on their website as to how to control the raging drosophila.

The Old Farmer’s Almanac has this advice:

You may want to try trapping the flies by inserting a paper or metal funnel into the mouth of a quart jar baited with bits of overripe fruit. The flies will get into the jar, but they will not be able to get out. To decrease the number of fruit flies outdoors, promptly get rid of any “dropped” fruits or vegetables and keep all garbage cans tightly closed.

Perhaps that’s what we’ll try next.


Alan's picture
Alan on August 31, 2004 - 20:43 Permalink

This is a job that calls for beer — what doesn’t. If you were to keep a small dish of reasonably sweetish ale around you may find that they are attracted to it but get stuck in it once they have too many sips and get that sleppy feeling. Works for garden slugs, too.

dave m's picture
dave m on August 31, 2004 - 21:39 Permalink

you can try a little red wine in a jar. seal it with plastic wrap. pierce the wrap with a series of tiny holes. works pretty well

Jacob's picture
Jacob on September 1, 2004 - 02:09 Permalink

I’m with Alan on this one. Beer works. I’ve had a small mug of beer on the back deck for weeks now. Earwigs, fruit flies, every bug seems to love getting trapped in it. Another thing that I tried to combat the fruit flies (out of pure frustration) was vacuuming the air. It actually worked for a while. I sucked in a bunch of them!

oliver's picture
oliver on September 1, 2004 - 02:56 Permalink

In fruit-fly labs, where flies are always escaping, they use more or less that funnel trick you quoted, Peter. If you do it at home during a plague I suppose you might accumulate so many flies in your vessel that an equilibrium sets in and flies escape as often as they fly in. In any case, I know there is the problem of how to empty the vessel without releasing the flies, because my aunt asked my advice on this. Here’s what I told her, which she said changed her life: After you have 10 or 20 or however many flies you can stand hopping around in your jar on your banana (or beer or whatever you put in), place the whole thing funnel and all in the microwave on high for about half a minute. The flies they will drop like…(well, you know). Then you put your trap right back on the counter or dump, rinse and re-bait it according to your personal hygeno-aesthetic standards.

barb's picture
barb on September 2, 2004 - 13:23 Permalink

Great idea with the beer. Vinegar also works just as well. And as for trapping them, my co-worker Barbara Nymark suggested this last year — and it works!
Cover your container tightly with Saran Wrap. Poke a few tiny holes in the top of the Saran Wrap. Somehow the flys can get in, but they can’t get out. Just like a lobster trap.
Soon you will have hundreds — thousands — of dead fruit flies marinated in vinegar. mmmmmmmmmmmmmm.

Lisa Howard's picture
Lisa Howard on September 2, 2004 - 19:19 Permalink

Tips to keep fruitflies down to a dull roar: Wash all your fruit with dishwashing liquid and water as soon as you get home from the grocery store. Keep all your compost outside.

oliver's picture
oliver on September 3, 2004 - 01:44 Permalink

Suddenly I remember something from the first philosophy lecture I ever sat in: “Time flies like an arrow. Fruit flies like peaches.” Can’t say it’s helped me much through life, but perhaps it’s applicable here.

Ken's picture
Ken on September 3, 2004 - 15:09 Permalink

Fruit flies & roadside trash — Waste Watch’s dirty little secrets.

Lisa Howard's picture
Lisa Howard on September 3, 2004 - 15:54 Permalink

Oliver, I think you’re on to something with the flying peaches. Fruit flies are also fond of flying cherries and flying first class. Maybe we could offer them a KLM ticket to Tibet or Moravia or something. Alternatively, take the peaches and throw them and hope the flies have read some philosophy.

Lisa Howard's picture
Lisa Howard on September 3, 2004 - 15:57 Permalink

Wait a second. I live near Moravia.

Marko Peric's picture
Marko Peric on September 6, 2004 - 20:06 Permalink

Apparently this is a widespread thing. I’m dealing with my own little infestation as well. What I’m trying, and it seems to be working well, is an open container (went with a 1 kg kraft peanut butter bottle) about half full of water, with a couple of tablespoons of sugar and a couple more of vinegar, and just a couple drops of palmolive dish soap. The sugar and vinegar seems to attract the flies effectively, and the soap destroys all surface tension on the water, so once they land, they sink and promptly drown. The bottle has been out for the better part of a day now, and there’s maybe a dozen fly corpses at the bottom, and virtually none left in the air.
Also, cleaning your small green compost container with soap and water is an effective way to get rid of a choice fruit fly breeding ground.

gwen's picture
gwen on August 5, 2005 - 01:08 Permalink

Thanks for the tips. I am trying Markos suggestion.