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Re:Wingless Fruit Flies

Beverly asked:
>What are you using for medium?  I've been making my own, and have problems
>with mold contamination that gets into the bottles when I add the flies.
>I haven't been able to find any of the food preservatives recommended and
>have been experimenting with lemon juice.  Does anyone have a good recipe
>for medium, or suggestions on mold inhibitors?

I prevent mold formation by using Drostab, sold by Daleco, 1-800-987-1120.
I have never had mold when I use it.  I use a pinch of Drostab per 8 oz of
culture medium.  Daleco charged about $23 for 60gm.  They also sell form 2d
AGAR at 80gm for $20.  I use canning jars, with the open lid. The jar lids
screw over a napkin allowing air into the jar - and I have never had
unwanted visitors get inside the jars with this arrangement.

My culture medium consist of 8oz of water, 1/2 tsp Agar, 1 Tblsp yellow
corn meal, 1tsp dark molasses, 2 1/2 Tblsp white corn syrup, 1/8 tsp dry
active yeast, and the Drostab.

I mix the agar and corn meal in water, bring to a slow boil, stirring
continuously for 5 min.  I remove this from the heat, stir in the molasses,
corn syrup, drostab, yeast.  I pour into the canning jars and allow the
culture to jell for one hour undisturbed.  This makes enough for 6 canning
jars filled with 1/2" of culture.

I then mixup a yeast and warm water mixture to the consistency of heavy
cream.  I pour this on top of the culture so that I have a thin film of the
yeast cream covering the cultures.

Within 2 hrs the fermentation process is underway.  I wait several days to
allow the alcohol fumes to evaporate.  During that time I keep the culture
jars covered with the napkin, so as to  prevent contamination by other

I ball up a napkin, put that into each of the culture jars, add the fruit
flies and let them sit for two weeks.  The cultures are typically good for
6 weeks.  I found the best yields are obtained by keeping the temperatures
constant (i.e., away from drafts, heating vents, etc.).

Augustine Rodriguez
Elk Mound, WI, USA