Someone posted a great idea about dusting any flies to be used in new cultures with flower. Any "pasengers" on the flies will fall off with the flower because they cant keep a grip onto the fly. You then obviously discard the flower and add the clean flies to the culture. As far as the curent problem, to prevent mites spreading to the other healthy cultures, sprinke an insecticide powder on the surface that the cultures are resting. When the mites try to spread they will be killed by the powder. I think any flea/tick/ant powder will work.
Mold is an easily cured problem. When you make your cultures, add some vineger. Problem solved. The one that is getting the mold in it now can be saved by spraying some vinegar inside the culture with a regular spray bottle.
Brewers yeast should be used at about one part brewers yeast and 3 parts potato flakes. That is what the flies eat (Im pretty sure)
Heres some info you might find helpful; its a post I wrote at a different forum about how I make my cultures.
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I now pre-mix all the following wet ingreients: Apple sause (half a jar), molasses (I dont measure, I just pour a good-looking amount in), a musshed up bannana, and some grape juice concentrate. I keep all that yummy slurry jarred up in the fridge untill I need a new culture. I have a zip-lock bag of potato flakes and brewers yeast pre mixed as well. (again at 3:1)
My procidure for making new cultures
1) Scoop 4 tbl spoons of my delicious refridgerated fruit mix into a culture container (from blackjungle.com)
2) pour in 2 tbl spoons each of water and vinegar
3) mix in 4 tbl spoons of the yeast/flakes mix
4) stir untill its nice and pasty. If is to thick or still flaky, I add more water/vinegar. Vice versa, if its too runny, I add more flakes. Simple eh?
5) throw in some window screen for larva to crawl on, a few flies, and close lid. Clean up takes a matter of miutes and best part is, you dont have to worry about preparing, boiling, pouring, storing, or cleaning any of that putrid power mix crap! Not only that, but I think when you store the power mix it looses a lot of its effectivness. With my method, all the active ingredients stay separate and fresh untill the last minute. So thats my method that I have been using succesfully for 4 months now.
Good luck!
-David Taylor
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"The day we would limit ourselves or adapt to the music scene, would be the day Opeth dies." -Mikael Akerfeldt; lead singer and genious behind the metal band Opeth.