catching fruit flies with salsa.

Every time we bring bananas into our home, fruit flies seem to arrive as stowaways. Usually, we just hide all of the fruit in the house and wait for the fruit fly population to die off. But it struck me this morning that it might be interesting to look for genetic mutations in fruit flies.

To begin with, we could build a homemade fruit fly trap. Fruit flies can be anaesthetized by placing them in the freezer for a little while. Once anaesthetized, we could examine the flies for phenotypic evidence of mutations like 18 wheeler or hedgehog using our handy portable microscope.

The only problem might be memorizing all of the genes that control fruit fly development.


Just so you know, if you build the paper funnel and jar trap, chunky salsa seems to be a great bait if you don't have any cider vinegar or banana slices on hand.

And yes, I have tested this empirically (with Meijer's Medium Chunky Salsa).

a paper funnel / jar trap containing many fruit flies after one hour

Note that after an hour, almost every fruit fly in the house has wandered in and is now incapable of figuring out how to leave. If you're curious, the flies remain trapped (despite the obvious opening in the bottom of the funnel) because their natural instinct (when not following a wonderful smell) when in an enclosed space is to crawl upwards, which means they never find the hole in the funnel. As it turns out, I've used this behavior in the genetics lab in order to anaesthetize the flies without killing them. Well, now I'm using the same behavior to remove them from my kitchen.

Monday, February 11th, 2002
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what you need

• 1 kitchen
• 1 jar
• 1 paper funnel
• 1 tablespoon salsa
• Salsa music (optional)
• Too many fruit flies