# Dead FF's



## Scootin Newton (May 15, 2014)

I made 2 small Cultures the other day using jars that I got from Petco,
About 75 % of the flies were dead by the next day
Possibly the medium was too wet?
Added yeast and the flies were added too soon?
Any insight appreciated
Thanks
Scootin-Newton


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## Engeli (Oct 3, 2014)

Scootin Newton said:


> Possibly the medium was too wet?
> Added yeast and the flies were added too soon?


Exactly, those are the two best explanations. 
Did you use excelsior or a coffee filter on top of the medium so that the flies could save themselves from drowning? 
If you add yeast, let the medium rest for 24 hours before you add the flies so that the CO2 can exhaust.
Take your time to experiment a bit with the medium and you will soon find out what will work best for you.


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## Scootin Newton (May 15, 2014)

I just started to try the coffee filters instead of excelsior, but I will wait longer to introduce flys as I just popped them right in after mixing
Thanks
S-N


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## FroggyKnight (Mar 14, 2013)

Engeli said:


> Exactly, those are the two best explanations.
> Did you use excelsior or a coffee filter on top of the medium so that the flies could save themselves from drowning?
> If you add yeast, let the medium rest for 24 hours before you add the flies so that the CO2 can exhaust.
> Take your time to experiment a bit with the medium and you will soon find out what will work best for you.


I do not wait to add flies to my cultures and I've never had a problem. If yeast is the issue, it isn't necessarily because flies were added too soon, but because too much yeast was added. VERY little live yeast is needed in a culture. Remember, a little goes a long way!

John


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## Scootin Newton (May 15, 2014)

5-15 grains


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## Dev30ils (May 1, 2012)

Don't you guys find your cultures a bit too hot after you first set them up? I let mine cool off for a few hours before I add flies.

I also switched to Repashy Superfly which doesn't require the addition of yeast. Saves a step.


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## tubbee (Aug 1, 2012)

I make my cultures on the Saturday and on Sunday add the yeast, excelsior, and the flies and have not had any trouble. Leaving it for a day also gives it time to cool off. At first I was adding right away and was getting dead flies.


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## Nick_ (Mar 24, 2008)

In line with the others above the CO2 could not be vented from the culture and they died from gas poisoning most likely. The tips above with letting the culture media settle/off gas will avoid the dead flies.


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## Erikb3113 (Oct 1, 2008)

I've never once let my cultures rest before adding flies. Granted I use very hot tap water, not boiling, but I have never had one die off like that.


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## Scootin Newton (May 15, 2014)

Thanks everyone for your tips and advice
Scootin-Newton


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## Ed (Sep 19, 2004)

Nick_ said:


> In line with the others above the CO2 could not be vented from the culture and they died from gas poisoning most likely. The tips above with letting the culture media settle/off gas will avoid the dead flies.


Working backwards.... Wait, What? 

Why would letting the culture sit for a length of time reduce the CO2 concentration in the cultures? The yeast and microbes have a huge food source and growth and respiration of CO2 is only going to rise as the culture sits. 

Fly deaths in newly setup cultures are highly unlikely to be due to CO2 poisoning. Remember that CO2 is heavier than oxygen and as the culture ages it will displace the oxygen from the lower levels of the culture. In addition, the flies can detect CO2 and as an aversion response will cluster up at the top of the cultures and only venture down to feed and/or lay eggs. 

Some comments 

Ed


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## nish07 (Mar 16, 2008)

My guess is either it was too wet (and you'd see flies sticking to things and covered in water) or the flies were probably old aged. You definitely don't wanna use too much yeast. 10-15 grains I think someone else said. It doesn't take much to colonize the top of the culture.

-Nish


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## Ed (Sep 19, 2004)

FroggyKnight said:


> If yeast is the issue, it isn't necessarily because flies were added too soon, but because too much yeast was added.


I'm highly skeptical of this claim. This is often thrown out there as an anecdotal reference but there are literally no support for it as a confirmed cause. 

On another anecdotal side, I've never been able to replicate it despite trying for many years. See how much yeast I used here as an example http://www.dendroboard.com/forum/food-feeding/88049-yeast-question.html#post779498



> =FroggyKnight;2248249VERY little live yeast is needed in a culture.!


The idea is that enough is added to 
1) help prevent other microbes from becoming established and
2) encourage earlier deposition of eggs. 
If too little yeast is added then your not going to achieve much in the way of of competition. Number 2 only requires a little yeast. 

Technically no yeast needs to be added to the cultures as the flies will transport microbes from the previous cultures. 

Some comments 

Ed


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## Dendrobait (May 29, 2005)

Ed: I guess that explains the behavior of flies added to new cultures!


I would think that when the yeast begins to use all the food C02 production would drop off substantially.


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## Ed (Sep 19, 2004)

It would be weeks before the conditions got to the point that the microbial life began to reduce CO2 production. Think about the length of time it takes for a culture to become too compromised for the flies to continue reproduction. During that entire period the microbes are also converting the basic media into biomass and releasing CO2. 

Some comments 

Ed


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## Nick_ (Mar 24, 2008)

Ed said:


> Working backwards.... Wait, What?
> 
> Why would letting the culture sit for a length of time reduce the CO2 concentration in the cultures? The yeast and microbes have a huge food source and growth and respiration of CO2 is only going to rise as the culture sits.
> 
> ...


Working backwards?

I am totally confused and a bit unsure where to start. It's the temperatures for activating yeast or in some cases for it to begin metabolizing sugars compared to that of a cooled portion which make my view cut and dry. When freshly mix batch of fly media is at its peak heat it will obviously accelerate the metabolism and result in a far higher release of ethanol and co2, dramatically more and easily seen if you use a method to measure the release compared to a cooled settled batch.
In a well ventilated container this would not be an issue, as with the mesh tops on some of the petco fly cultures and the industry standard of polyfabrics. With some of the newer ones they come with a sponge type cork that lends to less ventilation ( not the type from fly meat and some others, those seem to breath a bit better) is can quickly gas the culture. I donot even know if petco uses yeast in their cultures.

The concentration and temp go hand in hand, I'm sure you know this:
My thought train in the if the culture had poor ventilation (as incinuated in my post) they could easily gas the flies. You can gas vertebrates with yeast based co2 chambers let alone fruit flies. I made the mistake with a couple of my first tries using just a few needle holes for vents. Here I am rambling and I donot even know for certain the type of ventilation was on the cultures.... I do see your point on building over time but I was referring to the initial burst them the settle brought on by cooling before the rise.


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## Scootin Newton (May 15, 2014)

Nick_ said:


> Working backwards?
> 
> I am totally confused and a bit unsure where to start. It's the temperatures for activating yeast or in some cases for it to begin metabolizing sugars compared to that of a cooled portion which make my view cut and dry. When freshly mix batch of fly media is at its peak heat it will obviously accelerate the metabolism and result in a far higher release of ethanol and co2, dramatically more and easily seen if you use a method to measure the release compared to a cooled settled batch.
> In a well ventilated container this would not be an issue, as with the mesh tops on some of the petco fly cultures and the industry standard of polyfabrics. With some of the newer ones they come with a sponge type cork that lends to less ventilation ( not the type from fly meat and some others, those seem to breath a bit better) is can quickly gas the culture. I donot even know if petco uses yeast in their cultures.
> ...


Original post was the Petco steel/aluminum mesh


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## Nick_ (Mar 24, 2008)

Scootin Newton said:


> Original post was the Petco steel/aluminum mesh


Ah, the mesh ones have great ventilation. I've seen two other kinds at our local ones recently.


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## Ed (Sep 19, 2004)

Nick_ said:


> Working backwards?


I'm simply letting people know that I started at the last post and worked my way back through the thread. 



Nick_ said:


> It's the temperatures for activating yeast or in some cases for it to begin metabolizing sugars compared to that of a cooled portion which make my view cut and dry.


The problem is that you get a pulse of CO2 but it would have to be sufficient to displace sufficient oxygen in the entire container (keep in mind that the flies can detect CO2 and move up to avoid the gradient). In this case, the pulse is cause by a relatively low biomass of microbes. If CO2 was killing cultures we would see a lot more die offs during the subsequent weeks as the biomass increases and the CO2 accumulates. It's not as cut and dry as you propose. 

CO2 is heavier than air and the lids are going to minimize the ability of the cultures to allow circulation to reduce the CO2 gradient. This is also before we consider that you can also select the flies to be more tolerant to CO2. 





Nick_ said:


> When freshly mix batch of fly media is at its peak heat it will obviously accelerate the metabolism and result in a far higher release of ethanol and co2, dramatically more and easily seen if you use a method to measure the release compared to a cooled settled batch.


If the biomasses are the same then yes, but a greater biomass is going to increase the CO2 production. 




Nick_ said:


> My thought train in the i the culture had poor ventilation (as incinuated in my post) they could easily gas the flies. You can gas vertebrates with yeast based co2 chambers let alone fruit flies.


This is an apples and oranges comparisions. The ability to tolerate anoxic conditions isn't the same and Drosophila can even be selected for greater CO2 resistance. 

Some comments 

Ed


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