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Fruit fly culture Q's


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I picked up two vials of FF yesterday to start up cultures for seedlings, spider slings, etc. Despite both of them being labeled as "flightless", I got a vial of both flightless and wingless, so...bonus?

Anyway, the recipe I used was the simplest one I could find. Instant potatoes, powdered milk (I used goat's milk since it was the only one that was "whole"), sugar, and a pinch of baker's yeast on top to supposedly control mold.

(Opinions on that recipe are welcome)

I filled two 16 oz. ball jars about 1/3 full with the mix, tamped it down a little, and then put in some crumpled coffee filters for them to crawl around on.

I'm wondering a few things, since I've never tried this before:

1. About how often will I need to clean / replace the media, and will it be obvious, or should I be pro-active about it?

2. Do I NEED to harvest the adults regularly, even if there's nothing to feed them to at the moment? I wouldn't mind having two jars of each, but I doubt I'll need more than that for a long time. (Can I just dump them outside? lol)

3. As long as they don't crash / get infiltrated by wild FF's, will these original (rather small) cultures be sustainable, or should I occasionally introduce new genetic material?

Anyone who has an inkling is more than welcome to answer.
I have bred fruit flies before and I used a similar recipe with success. The media will be good for a few weeks, after which it will start to smell quite fermented. My biggest problem was that the larvae will eventually crawl out any air holes you may have in the jars. If you end up having a mix of both flightless and wingless, you can just separate all the wingless out into a jar of their own and all of their offspring will also be wingless. I would make sure to harvest the adults regularly enough so they don't die and spoil the media further. Another issue I had was while taking off the lid to select flies for my plants, they just got everywhere withing a few seconds. I didn't have any way to knock them out so I used the old "put them in the fridge for two minutes trick and try to gather them before they speed back up" trick. Good luck! It may be easier to buy freeze dried bloodworms, but if you have a good system that works for fruit flies go for it.
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It sounds like a lot of media you are using. I use about a 1/4 cup of flakes in 32 oz Mason Jars - about half an inch. I just use potato flakes, water, sugar, a pinch of mold inhibitor (bakery supplies), some brewer's yeast (for nutrition), a splash of unpasteurized apple cider vinegar and a few grains of baker's yeast. The baker's yeast starts the fermentation process and the flies live on the fermentation and vinegarization products - the vinegar supplies the acetobacteria for this process. I've been growing my cultures from the same starter batch for 6 years or so.

It is recommended you start your new cultures from the first couple of generations of your previous culture - you tend to keep the cultures more vigorous if you do this.

You can plug the jar with some open cell foam or cover with a paper towel or coffee filter paper - there is enough air exchange with these materials.

If the culture gets contaminated with wild fruit flies it is a simple matter to select out the flying ones by letting them fly out of the jar. Shake them down, open the jar and the flight capable ones fly out. If you do this every day eventually the flight or wing genes will been selected out of the population. I've had to do this once.
The large specimen tube type containers can work well. Since fruit flies invariably march up towards the light (they've apparently seen the movie "Poltergeist" too many times), the tubes are a convenient size allowing you to turn the tube upside down before taking the top off so they move back up towards the media end of the tube. Gives you a bit more control over how many you shake out.

As NaN mentioned, the spongy cell foam works well to plug the exit whilst still allowing some air exchange.

I appreciate all the responses.

For the jars, since the lids come in two parts, I'm just leaving out the center plate and cutting a piece of fine thread-count cloth to cover it, held down by the outer ring. It's working marvelously. They're loving the conditions in my grow tent, where it stays warm and humid, and the vial cultures are exploding. I just transferred another 30-40 flies to one of the jars.

Refrigerating them for a couple minutes (as Eric mentioned) is working wonders for making them more manageable.
When I was cultivating these, i used a simple mix of masa, dab of honey and of course yeast.
I've cultured fruit flies on a consistent basis for about the last 4 years as a staple food for poison dart frogs. Here's what I do:

1) The cup- I culture mine in those clear 32 oz plastic deli cups using the vented lids. (Do a search for fruit fly culture cups, and you'll find what you're looking for.) These can be cleaned and re-used many times if you want to and the lids allow proper air flow while still preventing escapees.

2) Media- Mine is similar to yours. I use 8 cups of instant potatoes to 2 cups BREWER'S yeast (the protein supplement) to 1 cup powdered sugar. The brewer's yeast is necessary because it provides the protein source on which the flies depend. If you go with something other than this ingredient, make sure it has adequate protein. You don't have to add baker's yeast. This is used as food for the adults, but they track enough of it on their legs to inoculate the new culture when one is started. Not adding more is recommended because using too much can cause a spike in CO2 and possible culture crash.

3) Pupating substrate- Most people add some kind of material that rises above the media to allow for more surface area for the larvae to climb and pupate. Whether that is excelsior material (wood shavings), coffee filters, paper plates, plastic Easter grass, plastic craft grid, etc doesn't necessarily matter. Some can be re-used, so choose what you prefer.

4) Making new cultures- My culture schedule goes something along the lines of: 1) make initial cultures, 2) when these begin to boom, make generation 2 3) when these boom...generation 3. It works out to roughly a new generation every two weeks. I like to keep three generations going at all times (one past-prime, one currently booming, and one just made). When choosing flies for the new cultures, it is actually advisable to mix flies from the past prime and current cultures. The reasoning behind it is that if you only select those currently booming, you are actually selecting for flies adapted to the early media conditions. This can cause cultures to crash sooner since the flies can't handle the conditions are the culture media begins to break down.

Other notes- In my experience, you do not need to add new flies to your system to keep them going. By mixing old and current cultures, you should be able to sustain your populations indefinitely. I've only had to buy new flies once in the four years, and that was at the beginning when I wasn't as experienced and let them crash. Try to keep old cultures (generation 3) in an area away from the newly made (generation 1) cultures. Mites can be a problem causing crashes, and by separating these two, you take precaution to prevent that. Temps in the upper 80s can correct the genetic pathway that codes for the flying protein, but flies also produce best at the mid-upper 70s.

This is all I can think of off the top of my head, but feel free to ask questions, and I'll do my best to answer.
Great information from everyone. I thought I would have something new to add but it has all been covered very well. Ill just throw in my similar recipe & a neat trick when transferring or feeding :-))

Media Recipe: yeast, instant potaoes, sugar, fish flakes (good supplemental vitamins in these), corn meal, apple juice.

Container: I breed in 2 liter bottles with sponge stuffed in place of lid. No air holes & no escapes. No need to clean & pretty much impossible. Harvest 75% or fruit flies or release them bi-weekly so they do not die in container.

Substrate: I use the mesh plastic red bags onions, garlic, or potatoes come in. Works great.

Feeding Trick: Place container in the freezer for a 1-3 minutes before feeding. This will effectively slow them down & prevent them from getting everywhere. Just tip over and tap em out... simple as that. Your media should be thick enough to not pour out.