Fight Back Against Fruit Flies!
Q. I recently noticed fruit flies near the 'Worm Factory' composter my daughter gave me for Christmas, which sits in a corner of my kitchen. I was thinking about treating it with the BTI granules I use to control fungus gnats on my house plants, but am concerned it may hurt the worms. I have added more shredded paper to the top of the bedding area since I noticed the fruit flies, and I suppose that they might actually be fungus gnats, but I've treated all my house plants with BTI several times since fall. Thanks for any advice.
- ---Matt in Normal, IL
A. I've been using the exact same multi-level "Worm Factory" for a year and a half to process our kitchen waste into plant-feeding worm castings, and haven't seen any fruit flies near it—even when our kitchen was infested with them recently; so I suspect improper worm bin care here.
Normal Matt's mention of adding more shredded newspaper makes me suspect he might not have been keeping enough bedding on top of the garbage in his bin. For once in my life I actually followed the directions, and have covered every new tray of kitchen waste with a lot of moist shredded newspaper; and I'm pretty sure that's why our kitchen fruit flies never showed up around the bin in the room next door—they're just not attracted to well-buried scraps.
And if Matt's house plant fungus gnat problems are so severe that he needs to repeatedly treat the soil, I suspect they just might be the culprit. Luckily, those all-natural BTI granules harm only the larval forms of flies that breed in moist areas—like mosquitoes, black flies and fungus gnats. So go ahead and water some into that worm bin. And stop overwatering the houseplants!
Q. We seem to have hatched a herd of fruit flies in our house. How can we get rid of them without constantly clapping our hands together and killing them off one by one?
- ---Amy in Glenside, PA
What can we do to eliminate the little flies that come in with vegetables? Is there a pheromone trap? Thanks for your help.
- ---Eve in Clinton,
A. Fruit flies are pretty much an occasional inevitable if you eat a lot of fruit, especially fruit that needs to sit out in the open to ripen up—like peaches, bananas, mangoes, pears and such. If you catch an infestation early enough (as we did with one years ago) you can shut things down fast just by removing all fruit from the area. Without any fruit, a small colony will die off in a few days.
But I did not react quickly enough recently. While trying to figure out how to try and recycle the rinds from my new morning indulgence, squeezing fresh oranges for juice (a million dollar taste delight that costs about the same as buying juice in a carton), I let the emptied-of-juice oranges sit out in loose plastic bags in the kitchen, deluded myself into denying the reality of the first flying annoyances, and boom—we soon had a flock of fruit flies.
Pheromone traps? No. But our fruit flies revealed just as strong an attraction for red wine the first time I left a glass unattended; and like slugs in beer traps, quickly drowned in the alcohol. So I left out little dishes of red wine, which trapped some, but not nearly as many as my wine glass had. I figured they were having trouble flying back up out of the neck of the glass, so I poured a few fingers of my least finest red wine into a couple of empty bottles and trapped hundreds by the next morning.
Fruit flies are also famously attracted to, and drown in, white vinegar. So I put some vinegar into other long neck bottles—and the flies checked in, but did not check out. (It turns out that Gardens Alive has a fruit fly trap with a similar 'easy to get in; hard to get out design—which of course, I didn't find out about until after my infestation was over.)
But there was this one little Darwinian group that would not give up, so I cut up a fresh sheet of the sticky paper that goes under the pest-attracting light in my flea traps, attached some of it to the top of the 'compost crock' that holds our daily kitchen scraps and cut the rest into long strips and slid them down into the necks of the trap red wine bottles. More success!
Now there were just a few flying around—and my wife thought that she could make out two distinctly different kinds of little flies on the sticky traps. I had recently potted up a whole bunch of amaryllis and brought some Spring bulbs I was forcing up out of cold storage—could we have fungus gnats as well as fruit flies? I had the necessary BTI granules—which I mostly use to prevent mosquitoes breeding outside—so I watered all of our house plants with a batch.
And that was it. Flies gone; crisis solved; no toxins used. Now we just have to explain why all those wine bottles were sitting out when this year's Girl Scout cookies got delivered….