Thanks much, guys.
if I were you I would always keep a culture or two of the Melanogaster around as a backup.
I always have 2 or more melanogaster cultures going, and will definitely continue to do so just in case.

I start new cultures every 7 days
I do as well, at least with the melanogaster. I only had the one hydei culture to work with initially, but now with 3 going, one a week from the first 2, I think I can do the same there.

Oh! does anyone mix flies from new and older cultures when making a new one?