Lyanda recently described our semi-tongue-in-cheek experiments with using a Venus fly trap to catch fruit flies. As at least one commenter rightly pointed out, however, sundews (plants in the Drosera family) are much more suited to the task, covered as they are with rows of sticky little fly-attracting mucilage droplets.

This weekend Claire and I were headed past Seattle’s Indoor Sun Shoppe, where they are mad for carnivorous plants, so we stopped in to pick up a sundew for some additional experimentation. While we were there Claire also bought a pitcher plant, completing our sample collection of the triumvirate of classic carnivorous plants: Venus fly trap, sundew, and pitcher plant. (Though as it turns out, there are more than 600 carnivorous plants across a dozen genera – who knew?! Time to start shopping for a butterwort… )

In third grade Claire had done a wonderful school project that included learning about and drawing these plants, but she had never seen most of them in person, and was fascinated by all the varieties the shop had on display. The sundew she picked is a lovely Drosera Adelae. And the pitcher plant is labeled a Sarracenia Leucophylla – though it’s likely a hybrid; true Leucophyllia, a native of the US gulf coast, are supposed to have very white pitchers. (Both our plants were cultivated by Courting Frogs Nursery in Stanwood, Washington).

Our pitcher plant, labeled a Sarracenia Leucophylla.

Of the three, the sundew is indeed best suited to catching fruit flies, which have continued their little red-eyed reproductive frenzy in our food scraps bin. Per the shop’s instructions, all three plants have been living on a sunny windowsill, but when I parked the sundew near the kitchen scraps, several of the circling fruit flies got promptly snagged in its sticky drops of mucilage.

I confess, annoying as the fruit flies are, it did tug at my heartstrings just a little bit to watch through my macro lens as this little guy struggle against the sticky predicament in which he found himself. Fruit flies don’t seem to be quite large enough to trigger the sundew’s movement response, in which they will actually wrap a fly in their sticky protrusions, so this guy just gradually struggled himself into more and more of a sticky bind.

Our carnivorous trio has not exactly brought our fruit flies under control, but they have been fun to learn about with Claire. Did you know that sundews (the genus Drosera) are a large family with over 180 plants, examples of which can be found almost everywhere in the world? Or that they need bright sunlight because they are so covered with fly-trapping appendages that they are weak photosynthesizers? Or that the sticky stuff is mucilage, like you find in aloe vera, or in okra, or on envelopes?

Here in the northwest we have a native, Drosera Angelica, whose range includes Washington. We’ll have to keep an eye out next time we’re in a bog!

Fruit flies are sometimes a little light to trigger the snapping mechanism of the flytrap, but they do stick to the fly-attracting substance the plant produces, and even this one little plant has managed to catch several flies.  We’re going to add a sticky sundew (another carnivorous bog plant) to our Botanical Anti-Fruit Fly Force.  And while it’s admittedly not making a huge dent in the fruit fly population, our new trap sure does entertain us.  Even Claire, our radical little bodhisattva vegetarian, gets in on the fun, feeding the plant flies she catches in the chicken coop.  “It’s gotta eat,” she says.

If you obtain carnivorous plants from a nursery, make sure they have been cultivated, and not torn from fragile bog habitats.  Most nurseries are ethical about such things, but it’s worth asking where their carnivores come from.  Keep the plants very moist, preferably in a bowl of water.

The fruit fly life cycle is crazy-fast–egg to adult in seven days– and it’s hard to match their menacing tenacity.  The very best way to control fruit flies is scrupulous sanitation:

• Keep fruit with even the tiniest bit of broken skin in the fridge.
• Wipe counters, wash dishes, rinse out sinks immediately.
• Wipe the edges of open wine bottles, and keep them in the fridge if you can (just one fruit fly in the bottle with give the rest of the wine a sick-sweet taste).
• Even with their skins on, bananas are great fruit fly attractor, so it’s best to avoid them (who needs bananas anyway, with all the gorgeous local produce to be had?).
• Take out your compost scraps twice a day, and keep them covered between-times.  Ditto the gargabe can.
• Make a simple trap by dropping a few of their favorite foods (skinned plums, tomatoes, balsamic vinegar, wine…) in a bowl, cover with plastic wrap that has little holes poked in it–the fruit flies will get in, but look at how tiny those brains must be; they won’t get out.
• And just for fun, add a Venus flytrap or two!

Look up close--their eyes are red...

PS: This post now has a follow-up, Sundews: The Best Carnivorous Plants for Catching Fruit Flies.

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