# Thar be mold in me culture!



## Mantis House (Aug 6, 2018)

I recently bought a small vial of d. Hydei flightless flies, and after trying to make my own culture (which exploded with molt on day 4), I decided to evacuate them back in to the original vial. A little molt started to form, and I basically gave up all hope, and just let them be. The molt covered the top of the media, and I figured it was only a matter of time before they all died. When I looked at them tonight, not only did I notice that the majority of the mold was gone (I circled the remaining in yellow), there are dozens of small, maggots in the bottom (you can make out a few in the pic). 





Is mold in the culture normal? I’ve read that it is bad, but the flies never laid eggs until the mold was present. Is it a coincidence, or is that how it is supposed to work? They’ve eaten nearly all of the mold, so I feel a little better about it. The culture is three weeks old as of yesterday, so they should have been producing by now. Did they just take a little longer than normal to start multiplying?


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## Predatorhousepet (Aug 7, 2018)

If you made the medium correctly and added a significant number of flies to seed, getting mold after only 4 days seems unusual. How did you make the culture?

If the flies are reproducing and the mold has nearly disappeared then it seems like the culture is back on track regardless of how it started.


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## Mantis House (Aug 7, 2018)

@Predatorhousepet

the media is just the stuff that I bought the flies in. It saws it’s supposed to last 5 weeks, but it wasn’t going to last that long 

the stuff I made was potatoes, water, vinegar, and a pinch of yeast


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## MantisGirl13 (Aug 7, 2018)

I used the same recipe and the same jars as you (containers from PetSmart ff cultures, right?) I had a lot of mold problems too. I would suggest using a wider, larger jar and a lid with tissue paper ventilation. I started using different containers with more ventilation, and I also sprinkled cinnamon on the top of the medium to keep down mold. I have had no mold problems for weeks since. Try it! 

- MantisGirl13


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## Mantis House (Aug 8, 2018)

Thanks! I read a lot about the cinnamon, but I wanted to try the actual recipe first. I’ll definitely try that, since I’m planning to upgrade the small vial into a jar or something.


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## MantisGirl13 (Aug 8, 2018)

Good luck! Definitely use a jar with more ventilation!

- MantisGirl13


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## Mantis House (Aug 8, 2018)

@MantisGirl13

just out of curiosity, how big of a container can I use? There has to be a point where it is too big. Most places sell them in 32oz cups, but could they work in an even bigger cup, or would it not even be worth it?

which reminds me of my other question: when do I want to move from the vial to a jar? The maggots are climbing up the side of the vial, but there are still TONS in the media. Do I want to wait until they all become flies, or is it safe to move them now, with minimal casualties?


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## MantisGirl13 (Aug 9, 2018)

@Mantis House I am not sure how big you can go, but I know that it is better to have more than one medium sized culture. I would wait until most of the maggots are adult and then transfer them to several different cultures. You could also do an experiment using several types of media and see what works best for you. I use an empty small peanut butter jar for my cultures, and I just cut out the middle of the lid and hot glue tissue paper inside. it works really well, is big enough, and has enough ventilation. Let me know how it goes!

- MantisGirl13


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## Mantis House (Aug 9, 2018)

I’ll try that. I tried using a quart mason jar, and it seemed to work until the molt started. I’ll definitely try using some cinnamon  

How long should a culture last? So say I make a good, non-molding media, how long should it be before I completely move the flies into another container?


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## Predatorhousepet (Aug 9, 2018)

A fruit fly culture generally lasts about a month and will have 2 to 4 population blooms during that time. When the population explodes is generally when I harvest flies to make a new culture. When you make a new culture you'll need at least around 100 adult flies to set it up. More is better.


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## MantisGirl13 (Aug 10, 2018)

@Predatorhousepet Explained it, though I think that you don't need that many flies! I usually start my cultures with between 20-40 flies, and I have HUGE population blooms.

- MantisGirl13


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## Predatorhousepet (Aug 12, 2018)

You can get a culture started from only 20 flies?  Every time I've tried less than 100 it takes the culture a long time to get going and the yields are not that great. I guess that's acceptable if you are only feeding one or two mantids but I have a lot of nymphs so I need big yields fast.


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## Synapze (Aug 12, 2018)

.


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## Predatorhousepet (Aug 12, 2018)

Hydei take a lot longer to get going than melanogaster flies. I found this in an image search comparing the life cycle of each culture.


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## Predatorhousepet (Aug 12, 2018)

Synapze said:


> I find that if I start with any less than the amount pictured below, it takes too long for them to start producing. It will probably be 3 weeks before the culture pictured below gets fired up.
> 
> View attachment 11201


Yes, I use about that amount too. 100 is just the absolute bare minimum to get a good yield in my experience but it does take longer the less you use.


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## MantisGirl13 (Aug 13, 2018)

I use about 20 per culture and I have lots of larvae in less than a week!

- MantisGirl13


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