# Trouble starting fruit fly cultures



## azbombero (Dec 4, 2009)

I am hoping for some advice. My fruit fly cultures are not producing flies. I have 2 different types of media from different sources. I follow directions exactly, measurements are spot on, boiling the water, adding a touch of yeast, and adding at least 100 flies. I'm getting maggots, but then the cultures seem to die without any flies. The media seems to turn "soupy" after the maggot phase.....

I am keeping all the cultures in a giant Rubbermaid blanket box, to keep the smell down. Would this in any way effect the cultures? 

Thanks!

Chad


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## FrogTim (Oct 1, 2015)

Try less water. If your rubbermaid is air tight it may be too humid. Are the larvae at the top of your containers? This is a sign there is too much moisture.

Also, I found my best results were when media was damp but there were small 'powdery' patches instead of all the media being saturated. After a few days the moisture evens out. 

It's easier to add water than take it away. So start with less.


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## Ed (Sep 19, 2004)

azbombero said:


> I am keeping all the cultures in a giant Rubbermaid blanket box, to keep the smell down. Would this in any way effect the cultures?


Possibly ... if there is excess CO2 building up you could be smothering the flies. 

If the cultures are too dry in the beginning the flies will pupate close to the surface of the culture and if the culture then becomes too wet, the pupae can drown. 

More importantly what kinds of flies are you rearing and how long are you waiting before giving up on the culture. 

What instructions are you following and what media are you using?> 

some comments 

Ed


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## chillplants (Jul 14, 2008)

I make my cultures a little on the dry side, kind of like chunky mashed potatoes. It liquifies within a few days after the pupae start moving around. I also use a box with lid to help keep the smell down. I make sure the lid is loose enough for air exchange and I open the box every other day for feedings. The lid stays off for several minutes while I get all my feedings done.


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## scooter7728 (Sep 1, 2014)

soupy sounds like too much water, I always make my mel cultures drier and hydei cultures moister.


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## gope (Jun 26, 2014)

So far I've used NEHERP & Genesis media and all I ever smell is a faint, pleasant cinnamon odor.


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## Alan (Jan 12, 2005)

I'm guessing that the box you are keeping them in is allowing too little air circulation and causes moisture buildup.

A healthy culture shouldn't smell like more than yeast until it really starts producing. Even then - you should have to be very close (in your face) to smell the culture.

Are you using vented lids? Are you stacking them?


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## Ed (Sep 19, 2004)

chillplants said:


> I make my cultures a little on the dry side, kind of like chunky mashed potatoes. It liquifies within a few days after the pupae start moving around. I also use a box with lid to help keep the smell down. I make sure the lid is loose enough for air exchange and I open the box every other day for feedings. The lid stays off for several minutes while I get all my feedings done.


Your pupae should not be moving, I guess your referring to the larvae. 

The liquifaction is most likely due to insufficient moisture leaving the cultures. 

The amount you open the container does not provide enough to really be considered a sufficient air exchange. CO2 is heavier than air so it is going to remain in the tub and cultures unless you actively displace it. The tub is also going to prevent excess moisture from evaporating and this can also contribute to an offensive odor. 

As others have noted there really shouldn't be that bad of a smell to the cultures. 

Some comments 

Ed


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## abIngenui (Oct 14, 2015)

Normally when I start a culture, I set the mixture up and throw in the active yeast. They do their thing, and when bubbles stop appearing I throw in the flies. This allows the yeast to die off and stop producing carbon dioxide, all the while creating a nice happy, somewhat sterile environment for the alcoholic maggots. 

As far as smell goes, my cultures never really smell until they crash. So if your culture smells, something has gone wrong and it has succumbed to dead maggot-eating bacteria.

As to the liquidy-ness, my cultures are normally pretty chunky. As the maggots eat, they will liquify the media. Overly liquid media essentially drowns the maggots. When the culture is chunky, they can burrow and act as little hydraulic pistons that suck air into their chambers because the culture can at least maintain enough form to do so. I've noticed that with more liquid cultures, the maggots mainly reside on the surface. If you see it getting too liquidy, then you can roll up a papertowel and wick some water away from the bottom.

I also make my own cultures from scratch and don't use any premade stuff, so I have no idea on that end.


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## Ed (Sep 19, 2004)

abIngenui said:


> Normally when I start a culture, I set the mixture up and throw in the active yeast. They do their thing, and when bubbles stop appearing I throw in the flies. This allows the yeast to die off and stop producing carbon dioxide, all the while creating a nice happy, somewhat sterile environment for the alcoholic maggots.


Unless your waiting weeks the yeast isn't dying off. Its still alive and there are other microbes growing and producing CO2. This also ignores the fact that the flies are going to be producing CO2 throughout their entire lifecycle. 



abIngenui said:


> As far as smell goes, my cultures never really smell until they crash. So if your culture smells, something has gone wrong and it has succumbed to dead maggot-eating bacteria.


BS. A culture can have a bad smell without anything killing the maggots and the live culture is the norm.... 



abIngenui said:


> Overly liquid media essentially drowns the maggots.


This is only a problem if the culture media is so runny that the maggots sink to the bottom (which is very runny). A culture like that would have everything sink to the bottom of the culture and would in all probability not be able to be saved. It certainly couldn't be turned to collect the flies without it all pouring out like a melted milkshake. 

Some comments 

Ed


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## TheHarlequin (Dec 11, 2015)

azbombero said:


> I am hoping for some advice. My fruit fly cultures are not producing flies. I have 2 different types of media from different sources. I follow directions exactly, measurements are spot on, boiling the water, adding a touch of yeast, and adding at least 100 flies. I'm getting maggots, but then the cultures seem to die without any flies. The media seems to turn "soupy" after the maggot phase.....
> 
> I am keeping all the cultures in a giant Rubbermaid blanket box, to keep the smell down. Would this in any way effect the cultures?


I'm not sure what type of fly you're culturing, but in my experience, melanogasters are remarkably resilient.

It's hard to say without more info, but I'd check the following:

- Buildup of something, especially CO2 if your box is unvented. Keep in mind that yeast produce a great deal of CO2 and can suffocate a culture rapidly.

- Larval parasites/pathogens. I've personally not dealt with parasites in Drosophila, but both invertebrate and bacterial parasites/pathogens can infect a culture. Typically, a parasitic bloom will occur just behind a host bloom. If you're seeing that pattern, it might be best to sterilize and start with new stock from a different source.

Best


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