Oh little fruit flies, how I love thee! We had to keep fruit flies and track mutations in my intro to genetics course. We would put them on these little fabric platforms and pump CO2 through the fabric. This would anesthetize them so we could look at them under a microscope and count things like how many had white eyes, deformed wings, etc. They really are the workhorse of genetic studies...they should build a statue of a fruit fly next to the monument to the laboratory mouse!