# Fly Culture Media



## JJuchems (Feb 16, 2004)

I have been reading the old post on homemade fly media and the use of Brewer's Yeast vs. Baker's Yeast. Is their a significant difference in fly production brewer’s yeast? The bellow recipe is what I have been using for the last five+ years. If I start using Brewer's, should I add more than a teaspoon of brewer's in place of Baker's?

1 cup of instant potato flakes
1 tablespoon of powdered sugar
1 teaspoon of bakers yeast
40% water and 60% White Vinegar until a light mashed potato constancy.


----------



## Minois (Dec 28, 2007)

Well, Matt gave me his recipe and he uses both... So I am impartial to your poll. Hope it goes well!


----------



## JJuchems (Feb 16, 2004)

I am trying to make the choice if I should start using brewers yeast. I tracked down a local source, and with the increase number of frogs I am now keeping I want to get the most from my cultures.


----------



## flyangler18 (Oct 26, 2007)

I believe that brewer's yeast is nutritious to the larval stage of FF, and baker's for the adults- there's room in your mix for both.


----------



## asilsdorf (Sep 7, 2005)

I concur with Jason, I use both in my mix.

My understanding is that the brewers yeast is a dead yeast used as nutrition for the larvae and the bakers yeast is a live yeast used to convert the sugars in the mix to sugar alcohols for the flies to eat.


----------



## dragonfrog (Feb 16, 2006)

I too use both. But for those who may be reading this as a newbie, use very little of the bakers yeast (10 grains or less per culture) as the CO2 formed will kill the flies if you put in too much active (baker's) yeast. 
Most of us are aware of this, just warning those who may not know.


----------



## Ed (Sep 19, 2004)

The flies also transport in thier own yeasts.. If you are concerned about the risks of CO2 and the amount of yeast tilt your cups for the first week or so..... 
I routinely use more yeast grains in my cultures..... 

Ed


----------



## JJuchems (Feb 16, 2004)

Well my ADD got the best of me and I made cultures using Brewers Yeast. 
I used: 
3 cups of potato flakes
1/2 Cup of Brewer's Yeast
3/4 Cup of Powdered Sugar
60/40 mixture White Vinagar and Water 

Few grains of Baker's Yeast on top. 

I guess I will see how well the cultures come out. They better be good! They smell is aweful using Brewer's Yeast.


----------



## dragonfrog (Feb 16, 2006)

The smell is probably from the vinagar, not the yeast.


----------



## JJuchems (Feb 16, 2004)

I have been doing this for years and thought I would give another yeast a try. I know it is not the vinagar. I bought the Brewer's yeast at GNC. It is not just the yeast, but a whole new smell. This should be interesting. I think I am going to change the mix next time and reduce the amount of Brewer's yeast and add more than a few bits of baker's yeast.


----------



## Matt Mirabello (Aug 29, 2004)

JJuchems said:


> 3 cups of potato flakes
> 1/2 Cup of Brewer's Yeast
> 3/4 Cup of Powdered Sugar
> 60/40 mixture White Vinagar and Water


Similar to my recipe but I use nutritional yeast (similar to brewers yeast) but I use 1/2 cup of it to 8 cups of mashed potato flakes and 1 cup of powdered sugar (no vinegar but i do mix molasses into the boiling water). No research behind that number, just a method that was told to me by another frogger.


----------



## Greg (Dec 25, 2007)

I would use bakers yeast, but the only reason I would use that yeast is because I have it on hand down in the kitchen. Overall I don't think it has that much of a difference which type of yeast is used.


----------



## Matt Mirabello (Aug 29, 2004)

I think people are missing the point that has already been made. Brewers yeast is NOT alive and serves a different function than bakers yeast which IS alive. They just both happened to be called yeast since they are yeast (one is dead and dry and the other is alive or active)

The brewers yeast adds nutrients for the flies, it is in the same category as potato flakes, molasseses, vitamin powder, powdered sugar, etc

The Bakers yeast is not a nutrient it is a living part of the culture like a fruit fly or a mite or a bacteria. It eats the media changing it for the benefit of the fly larvae. It keeps harmful bacteria at low levels and partly digests the media into a substance the fly larvae (and maybe the flies) can use better.

I am sure this has been covered before but I could not find the thread that went into detail on the subject.


----------



## SCHMUSTIN (Sep 24, 2014)

Very good read, thanks guys.


----------



## oddlot (Jun 28, 2010)

Vinegar definitely makes it stink.I use methyl Paraben instead of vinegar now with brewers yeast and a few grains of bakers on top and it doesn't smell at all anymore.I also use cinnamon which smells better if for nothing else. Some say it helps with mold too,but I don't know,but I like the way it smells anyway.


----------



## packer43064 (Nov 30, 2010)

oddlot said:


> Vinegar definitely makes it stink.I use methyl Paraben instead of vinegar now with brewers yeast and a few grains of bakers on top and it doesn't smell at all anymore.I also use cinnamon which smells better if for nothing else. Some say it helps with mold too,but I don't know,but I like the way it smells anyway.


Cinnamon is a natural mold inhibitor.


----------



## Kerrek (Jul 11, 2013)

I started putting a little bakers yeast in my Repashy cultures a couple months ago and my fly production has gone way up.


----------



## Ed (Sep 19, 2004)

packer43064 said:


> Cinnamon is a natural mold inhibitor.


At a concentration where cinnamon acts as a mold inhibitor it also inhibits the growth of yeasts which are desirable in the cultures. So if you have enough cinnamon to inhibit mold growth, your inhibiting the yeast and that does not bode well for your cultures.... So I have significant reservations that what people are adding really does anything for mold.... 

See for example Bullerman, L. B., F. Y. Lieu, and Sally A. Seier. "Inhibition of growth and aflatoxin production by cinnamon and clove oils. Cinnamic aldehyde and eugenol." Journal of Food Science 42.4 (1977): 1107-1109. 

I should also note that the active oils in cinnamon are toxic to flies above a certain threshold and even well below that threshold shows significant depression of the nervous system of the fly.... 

As with other voodoo husbandry techniques I doubt that the cinnamon is really helping with mold/production.. The only thing that is of value is if you think it makes your cultures smell better.... 


Some comments 

Ed


----------



## Judy S (Aug 29, 2010)

Ed...can you explain about tilting the cups? Is that for more surface exposure? Also, I think the mystery of why I had three out of four cultures crash...maybe too much bakers yeast...thought I had made them the same as before...and how long will Brewers yeast last? I have a really big container which I have not used...have had it quite a while. There seems to be more art than science to successful FF cultures...


----------



## packer43064 (Nov 30, 2010)

Ed said:


> At a concentration where cinnamon acts as a mold inhibitor it also inhibits the growth of yeasts which are desirable in the cultures. So if you have enough cinnamon to inhibit mold growth, your inhibiting the yeast and that does not bode well for your cultures.... So I have significant reservations that what people are adding really does anything for
> 
> mold....
> 
> ...



Thanks for the information. I use vinegar, or methyl paraben. Don't like cinnamon too much.


----------



## ecichlid (Dec 26, 2012)

Ed said:


> As with other voodoo husbandry techniques I...


 Please do not criticize us who use voodoo for FF culturing. As I stated in the past, chicken blood and chanting does wonders for fly production.


----------



## Ed (Sep 19, 2004)

Judy S said:


> Ed...can you explain about tilting the cups? Is that for more surface exposure? Also, I think the mystery of why I had three out of four cultures crash...maybe too much bakers yeast...thought I had made them the same as before...and how long will Brewers yeast last? I have a really big container which I have not used...have had it quite a while. There seems to be more art than science to successful FF cultures...


Hi Judy,

People often forget that CO2 is heavier than air. As a result if there is too little air circulation over the cultures the CO2 will form a anoxic level in the culture(s) starting at the bottom and decreasing upwards. This can lead to suffocation of the larvae and possibly the adults. When this occurs you will generally start to see multiple size classes of larvae migrating out of the media to try and avoid suffocation. This is most likely to occur when the cultures are stored inside other containers as that prevents the air flow over the cultures from happening. 

Some comments 

Ed


----------



## Ed (Sep 19, 2004)

packer43064 said:


> Thanks for the information. I use vinegar, or methyl paraben. Don't like cinnamon too much.


I have significant reservations about vinegar as well. Many of the molds we want to keep out of the cultures are able to grow on acidic substrates furthermore some of them (Such as Aspergillus niger) reduce competition from other molds by significantly reducing the pH of a growth substrate (to below a pH of 4). 
Furthermore there are negative correlations on the growth of the larvae on acidic substrates with the more acidic the substrate the greater the correlation the negative correlation. I haven't chased down most of the references as of yet as its an area where I'm not exceptionally interested but one could start with the bibliography in this paper 

The Effect of Resource pH on Pupation Height in Drosophila (Diptera: Drosophilidae)
Journal of Insect Behavior, 1998, Volume 11, Number 1, Page 47 

Some comments 

Ed


----------



## Judy S (Aug 29, 2010)

This little old lady is having problems understanding all this ..... bet I'm not alone....


----------



## FroggyKnight (Mar 14, 2013)

Judy S said:


> This little old lady is having problems understanding all this ..... bet I'm not alone....


Where are you lost at? CO2 can build up because it is heavier than air and will push the air away. By tilting the cup, you can let the CO2 flow out of the cup instead of being trapped.

If its about the use of vinegar, Ed was just stating that it can encourage growth in some mold species by getting rid of the competition. It is easier for mold to colonize surfaces if it has no competition from other species.

John


----------



## Ed (Sep 19, 2004)

Judy S said:


> This little old lady is having problems understanding all this ..... bet I'm not alone....


Hey Judy,

People often discount the fact that many bacteria and yeasts release CO2 as part of their respiration so in addition to the fruit flies you have a pretty large number of things breathing in a partially sealed container. This can lead to CO2 gathering at the base of the container as it's heaver than oxygen. As a result the area closest to the media tends to have a higher CO2 concentration. This tends to form a gradient from the bottom of the cup having the highest levels of CO2 to the top of the cup having the least levels. The maggots and the flies have some ability to tolerate some CO2 levels but if the levels get high enough then the culture can smother. If there is a significant temperature difference between the bottom of the culture and the top, you can get the formation of air currents to help disperse some of the CO2. The same thing can happen if there is sufficient air movement over the top of the cultures. 

If you tilt the containers then your changing how the CO2 gathers in the cup. Think of a glass of water about half full of water. If you tilt it, you can get the air close to the bottom of the glass. This would represent oxygen getting down to the base of the culture more readily. 

In general, I suspect that CO2 poisoning maybe fairly uncommon as people don't tend to report the flies clustering at the tops of the cultures before crashing or that all sizes of larvae are migrating out of the media searching for a place to breath. 

Does that help? 

Ed


----------



## Judy S (Aug 29, 2010)

yup...so perhaps just automatically tilting the cups would enhance chances of better cultures? The three that I had crash seemed like they were going to be really big...now it does seem probable that I starved them of air..and perhaps too much baker's yeast sprinkled at the top of the media. And perhaps I put too many flies in the making of the new cultures...am sure that plays into it as well... Thanks so much....


----------



## Ed (Sep 19, 2004)

Judy S said:


> yup...so perhaps just automatically tilting the cups would enhance chances of better cultures? The three that I had crash seemed like they were going to be really big...now it does seem probable that I starved them of air..and perhaps too much baker's yeast sprinkled at the top of the media. And perhaps I put too many flies in the making of the new cultures...am sure that plays into it as well... Thanks so much....


Or you have genetics that don't tolerate crowded cultures. When do you harvest flies to start the newest culture? 

Some comments 

Ed


----------

