It's surprisingly difficult to get an estimate on the fruit fly population of California, or even just an average 'per unit area' figure.

Anyway, this fungus is already endemic in California, and I believe California has a major problem with this pest. I'd be surprised if there weren't at least a billion fruit flies active in California mid-summer.

As I said in a sibling comment, let's do some safety validation & deployment testing, but also let's not forget this is already out there.