Okay... I've got a confession, too. I made up the part about trying for a foot-tall fruit fly... I doubt there are any studies that specifically show sterility among fruit flies selectively bred for a large size... especially studies with the goal of producing a race of 12-inch-high monster-flies. :) It just seemed funny to visualize :)
But selective breeding for any number of traits tends to produce sterility.
"Studies" abound. Ask a dog breeder, a horticulturist... or google for "selective breeding" and "sterility".
Cheers.