Beer Or Sugar Water? For Flies, The Choice Is Pale Ale

Written by Joe Palca for NPR.org

Flies are attracted to glycerol, a chemical in beer produced during fermentation. Understanding more about the genes responsible for taste and smell in flies could help make powerful insect repellents.
Scientists in California think they’ve figure out why flies like beer. That may sound a bit trivial, but in fact it could lead to new ways of combating plant and animal pests.

That flies like beer is well known. “The attraction of flies to beer was first reported in the early 1920s,” says Anupama Dahanukar. She’s part of an inter-disciplinary program involving neuroscience and entomology at the University of California, Riverside. She’s been studying how flies recognize chemicals, so answering the question of why flies like beer is actually quite relevant to her research.

It’s not a simple question. Scientists are only just beginning to understand the basics of smell and taste in humans, so research on flies has been extremely helpful with that.

Since flies are well known to like sugar, it could just be that flies like beer because they can detect some residual sugar in beer. But Dahanukar suspected that might not be the case. So she planned an experiment. She would give the flies a choice between beer and sugar water, and see which they preferred.
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