Part of the show Superconductivity and Cooling Devices
Jean in Cambridge asked:
When fruit is rotting in a bowl, you get horrible black flies coming out of them. How do they get there?
Those flies are called Drosophila or fruit flies. They're the favourite friend of geneticists because they're very easy to do experiments on. Many animals use their antennae to detect chemicals given off by the thing they want to eat. Drosophila are in the environment pretty much all the time. They lay eggs, the eggs hatch, and in the warm environment of your house they can then fly around and home in on your fruit bowl. The other things that attract them are red and white wine. The volatile agents smell a bit like fruit because wine is made from fruit.