[DouglasKC]

I think you're confusing "generation" and "life span." Your model may be bad in other ways as well.

Generations would be even shorter. Life span for a fruit fly from egg to death is one week. Generations would be even shorter. I was being generous.

I don't care how it's set up. Set it up anyway you like. Find a shorter lived creature like a gastrotrich, some of which which has a 3 day life span.

The point being that surely someone should be able to make a fruit fly change evolve into something other than a fruit fly. Yet it hasn't happened. Why?

[puroresu]

A billion generations of fruit flies would lead to nothing but more fruit flies.

[VadeRetro]

The point being that surely someone should be able to make a fruit fly change evolve into something other than a fruit fly. Yet it hasn't happened. Why?

It's because of where you're setting the bar. To stop being fruit flies, a population would have to speciate, genus-ate, and then family-ate.

Fruit Fly:

common name for any of the flies of the families Tephritidae and Drosophilidae.

It might have to actually go a taxon higher than that (order), since the term "fruit fly" encompasses two families now. Speciations have been observed. That's more than what creationists usually admit as possible.