You may have seen this post on other forums, but I got a lot of replies about it so I'm reposting it here.

It's a mini HOW-TO for making fruit fly cultures. By no means this is a definitive guide. I tried a variety of methods, containers, recipes, etc. This is what works very well for me, so I thought I'd share it with you guys.

1st is the recipe for the media. This is very simple with no frills and it produces extremely well. It's also cheap !


Ingredients

• White Vinegar - The cheapest you can find. No need for Heinz here. Bottom shelf, no name.
• Hot tap Water
• White Sugar
• Brewers yeast - other types of yeast just don't cut it. Be sure to use brewers! (check your local bulk foods store)
• Instant mashed potato flakes (also bulk foods).
• Fleischman's instant yeast

Tools:

• Whisk
• Bowl
• Fruit Fly containers & lids
• Excelsior or Coffee filters

Make a mix of 50/50 water vinegar mixture. Add brewers yeast and sugar. Whisk until dissolved. Add potato flakes until you get a mix of consistency looser then apple sauce.

Let it stand for about 5-10 minutes until it thickens. It should now be as thick as apple sauce. If it isn't add more water/vinegar mixture. If it's too runny, add a bit more potato flakes and let it stand for a few minutes until it thickens.



Add about an inch of the media into the cup. I guess if you're into re-usable then you can use jars or even bottles. I don't like it and I refuse to clean the mess, so I just use the plastic 32oz fruit fly containers with meshed lids. You can get them here



Sprinkle a small pinch of instant yeast on top. Not sure if this actually works, but the popular belief is that the adult flies feed on this. I didn't notice any difference in production or life expectancy when I don't add it...but, it's not expensive, lasts a long time and doesn't really take that much more time, so might as well add it. Just a pinch.



There's probably as many opinions about the filler that you put into your cultures for fruit flies to climb and lay eggs on, as there are media recipes. A lot of people like to use coffee filter paper. Personally I don't. It gets wet, it's flimsy and sometimes falls out. If you like it and it works for you use it, if you like something else use that.



Excelsior works great for me, so that's what I prefer to use. It's expensive if you buy it at a craft store. It's cheap if you get it at a packing place of go to home depot early spring when their water fountains come in Don't ask, just take an empty box with all the excelsior you need and tell the cashier it's empty- they never seem to mind. I did that for a long time, then I needed it in the fall, home depot didn't have any, so I bought a bail of it for about $50. That was 2 years ago. I gave a ton to other people and I still have enough for the next 5 years! Get few guys, get a bail and your excelsior problem will be solved. I don't remember where I bought it tough...somewhere on the web at a packing place.



Make a little ball, shake out any loose threads and pack it into your containers. Make sure you press it into your media. You're now ready to seed your new cultures with fruit flies.



Before you add fruit flies from an old culture, be sure you inspect it for mites. If you have mites, well.... you have a big problem to deal with. I won't get into it here, so lets assume you don't have mites

Few things to remember when making cultures:

• Get yourself good anti-mite paper. Make sure it's fresh.
• Never leave your producing cultures on other surfaces other then the mite paper.
• Don't use very old cultures to make your starter cultures. Try to pick'em at their prime
• When you stack the cultures on the shelf, make sure the lids don't touch.

Add about 100 flies to each new cultures. You can add more, but be warned. Your culture will practically explode with maggots and fruit flies. If you leave too many flies in your culture, it may crash and shorten the useful life of your culture. It's better to add less flies and have it produce for a longer period of time, then have a huge population for a short time.



Above is a melanogaster culture that's packed with maggots. Like I said, you can get more maggots if you seed with larger number of FFs but this will come at a price, so don't be fruit fly greedy It's better for the culture to last you longer, so you don't have to make them as often.

Here's a closeup


I make my cultures probably once every 3 weeks. I make both melanogasters and hydei's



Here's a good tip that will make your fruit flies last much longer ! When I make new cultures I always make few extra that I don't seed. Just leave them empty. I make them my "Overflow" storage containers. If a fruit fly culture produces more then I can use, I'll throw the excess FFs into the "O" containers where they will be able to survive without a problem. This alleviates the strain on the culture that produces, which makes it last longer. You now also have all the fruit flies that you'll ever need in the overflow. This will also mean that you've SUPER seeded the overflow culture. Which is OK as this is just an "O" culture. It will still be useful for feeding off the adults, but remember it will also explode with a population when it matures. I don't use the Overflow cultures for seeding new ones. I only seed new ones from healthy cultures. The Overflows are great buffers to keep your cultures in check and not crashing. It's also great when your cultures are not ready to produce. Works great for me.



Here's how I keep my cultures. I've been doing it for several years, so I've got it down to a science. Before I needed many more cultures, now with the overflow containers my cultures are much healthier and produce much longer. I typically toss'em out when they still produce. I'd keep'em longer, but after about 3-4 weeks they tend to start to stink. I don't like stinky cultures, so off they go. I put the freshest cultures near the top and older cultures that I'm using to feed on lower shelves.

Hope you find this useful !

this word is intriguing,....can you pelase discribe the specs of anti-mite paper. who is producer? who is seller?

can you fax or scan me a copy of the product description.

ThANKS

great write-up marty..very helpul.

The anti-mite paper is a MUST. It's easy and keeps things mite free. I wouldn't be without it.

Are you sure if using the yeast is beneficial? In our genetics class we used "fruit fly food" which our prof told us was just the instant potatoe flakes.
Also we used stips from strawberry baskets as a filler for the flies to climb on. They're nice because you can stick them down into the feed as a ladder (we just used breeder tubes which are a lot smaller than your tubs) and if you want to reuse them you can just clean them up really good (boil them to be safe) and go again.

Do you ever find you run into a problem with inbreeding of the flies? I imagine there's a large enough number that mutant strains could be "filtered" out but just curious.

I'm not sure on this but I also thought the yeast was used to compete with mold and help keep it at bay.

Interesting about the overflow cultures, never thought of that.

Is that a concern? Mutant strains I mean. I don't have any frogs yet and am studing up on making cultures etc. for my frogs.

Heh.. We are already working with mutant strains of fruit flies, unless you really like the flying kind.

Fruit flies in the hobby are derived from stocks of flies that are highly inbred to start with. It isn't really a problem. You may be tempted to mix your flies with some other strain to increase the 'vigor' of your flies. Don't do this, you are likely to get all winged flies and that is a mess. Never mix fruit flies from two different sources, and even if they are from the same source you shouldn't mix them.

There should be no problem inbreeding flies. After some period of time you may notice your flies are 'tired', and aren't performing as well as they used to. That is almost certainly not a problem of inbreeding. I think it is most likely an accumulation of parasites of some sort. I had that very problem recently, so I just got some fresh stocks and started over. They will be good for another three or four years now, I'm sure.

Another thing. Make your next culture as soon as the previous culture hatches out. I think Marty mentioned this, but old flies are not as good breeders as young flies. It only takes a fruit fly a day to become sexually mature! Also, the generation time of mites is longer than the generation time of fruit flies. If you make new cultures as soon as possible, you keep mites to a minimum (they can't breed fast enough). I like to keep my new cultures in a different room than my 'producing' cultures, I move them in with all the rest only after I've started a new batch.

That's actually not a very good idea. If you use the flies from the first boom you will be line breeding the flies to have fast booms with low immune systems and the cultures over time will start to fizz out early. If you use old flies you will get hardier flies that live much longer over time, but will be slow to start booming and will be typically smaller overall size. It's best to use the flies a week to two weeks after the initial boom to start new cultures with to get the best of both genetics.

I think we'll have to disagree... Everybody has their own way, of course, but here is my logic.

Fertility might change with the age of the fly, but I can't see how that is a good thing. It can only go down. And flies don't have an immune system as we think of it. Certainly not one that develops over time. Flies have no acquired immunity, that is something limited to vertebrate animals. They do have innate immunity, of course. That is encoded in the genome of the fly. I don't really see how it is possible to change the genetics of the fly by fast breeding, genetics doesn't work that way. If you are thinking of natural selection, you need a diverse set of alleles for that to work. You have a very homozygous breeding population, there is really no way to alter the genetics of these flies short of random mutation. While I'd agree that mutations can happen, I don't think you are seeing it on a scale that makes enough sense to justify using older flies.

What you might be seeing is the effect of seeding your cultures with flies of different ages. If you seed your cultures with flies that are all a day old, then of course you will see a flush of flies at the beginning, your culture is timed to boom 14 days after you set it up. If you seed your cultures with a mix of different age flies, then you will most likely extend that 'boom' over a slightly longer period of time. I have no doubt that the flies will be smaller too, but not because of genetics or immunity, they will be smaller because the larvae are competing for resources (food, pupation spots, etc) with larvae of different ages.

Personally, I don't mind short acting cultures. If you keep your cultures too long you get mites. I don't ever keep a culture more than 3 weeks after it starts producing, and they produce pretty well over that period of time. I'd much rather set up new flies every two weeks than deal with mites and all the other hassle.