Culturing fruit flies for dart frogs

If you intend to keep dart frogs you have to get comfortable with the concept of feeding live foods. The staple of their diet is vitamin dusted fruit flies, typically Drosophila melanogaster and Drosophila hydei.

I used to culture three kinds of fruit flies, and my typical rate is 4 Drosophila melanogaster cultures per week, 2 Drosophila hydei, and 2 golden Drosophila hydei. This rotation proved to be more difficult to maintain than I liked, so I moved to culturing 12 D. melanogaster “Turkish Glider” cultures a week. This page walks you through the process I follow to make fruit fly media, prep fly cultures, and seed the cultures with fruit flies, as well as a new update for 2017 that details how I selected Turkish Gliders and how I store and rotate cultures to reduce my prep time.

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Making media and cultures

Deciding if making your own fly media is right for you

After about a year of purchasing commercial fruit fly media, I decided to try out making my own. During the process I kept commercial media on hand and ran my mix in parallel to the commercial mix. I saw no difference in the yields from the two mixes, so I stuck with my homemade media. The benefits of homemade are readily available ingredients, and a cheaper price.

Here is the pricing from two online vendors that illustrate the cost per pound (this calculation was performed in 2014). This does not include shipping:


Generally pricing for online vendors’ fruit fly media varies between $5 and $7 per pound depending on the quantity you purchase. You can get really aggressive pricing down to $3 to $4 if you buy in batches of 25 pounds or more. That’s a lot of media to store.

There are lots of fruit fly media recipes out there, and I chose a fairly simple one. Here is the breakdown of the fly media recipe I followed:


The most expensive ingredient for me was brewers yeast that I originally purchased from the health food store. I did switch to a commercal vendors brewers yeast to drive down my costs, but in a pinch, I can still pickup brewers yeast locally. You can see the cost per pound for home made fruit fly media is about $1.70. This is significantly less than the comparable 3 lb pricing for commercial fly media at $5 to $6 per pound.

My pricing does not include the cinnamon I sprinkle on top of my cultures to control mold. Commercial vendors typically use methylparaben for mold control, but again this is not easily sourced, so I prefer to use ingredients I can get locally.  I don’t use much cinnamon and I don’t add it directly to the media, so I did not include that in the cost.

You have to determine if the convenience of sourcing local materials outweighs the effort of having media shipped to you at the additional cost. Personally I find making my own fly media easy, and I like the security of being able to quickly make a batch of fly media if I unexpectedly run out.

Preparing fruit fly media

Here’s a shot of the fruit fly media ingredients ready to go:


I use instant mashed potatoes, powdered sugar, and brewers yeast. I mix them in a shoe box sterilite bin that I keep in the freezer:


First up is adding the potatoes. I use approximately 27 oz of potato flakes from the local grocery store brand:


In this case I used two boxes of flakes:


I then add 8 oz of powdered sugar. In this case it’s half a box:


Finally I add 2/3 cup of brewers yeast:






And then I stick the bin in the freezer. That’s it! Pretty easy, and cheap, fruit fly culturing media made with ingredients you can find close by.

Preparing cultures

Preparing fruit fly cultures is straight forward. I start by boiling water that will be used with the fly media that was prepared earlier:


While the water is boiling I layout my cups for my D. melanogaster and D. hydei cultures:

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I add 1/4 cup of media for Drosophila melanogaster cultures and 1/2 a cup for Drosophila hydei. I use more media in the Drosophila hydei cultures since I keep those for about 6 to 8 weeks, versus the 4 week life cycle of the Drosophila melanogaster culture:

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Once the fly media is added I place the tops on the cultures and label them. I write the date made on the lids for easy reading:

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And the date and type of culture on the side of the cup:


I bring the water to a rolling boil and add it to the cultures:

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I eyeball the water content. I used to measure, but I found the amount of water would vary seasonally so I started to judge the thickness of the mix by eye. Sorry it’s not more scientific.


Once the water is added I stir:


And repeat the process for all cultures:


I dust the top of my fly media with cinnamon to prevent the formation of mold:


Cinnamon has worked well for me over time, and it improves the smell of the cultures. I have found that it works better for me to lightly dust the top of the prepared culture rather than mixing larger quantities of cinnamon in the fly media mix. This also helps to keep the cost down. Now the fly media has been prepped, and dusted with cinnamon:


I then prepare coffee filters for a substrate for the fruit flies. I fold them in half, then smash them down into a cylindrical form:

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I use eight 12 cup coffee filters:

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I add the tops right away to keep the moisture in the cups:


And that’s it! One weeks worth of cultures prepped!


I let the fruit fly cultures sit for a few hours before seeding with fruit flies to allow them to cool. I also visually inspect the fruit fly cultures to ensure there is not too much condensation on the sides of the cup that could trap flies. Usually the coffee filters do a good job absorbing the water.

Preparing seed flies

I’ve had issues with mites from commercial fly cultures during my early frogging days. Since that time I have refined my culturing methods to include mechanical separation of mites from fruit flies to help reduce the transmission of mites from culture to culture. I’m not claiming this approach eliminates mites, but I can say that I have not had a mite boom or the loss of a culture from a mite infestation since I started sifting fruit flies. Here’s the approach I use:

I start with a kitchen flour strainer. This is a really fine mesh that catches Drosophila melanogaster, but it also can catch large mites:


I added a standard kitchen strainer on top of the flour strainer. The kitchen strainer can catch Drosophila melanogaster and Drosophila hydei, but some fall through. No mites are trapped by the kitchen strainer, so whatever flies are trapped in the kitchen strainer can be transferred to a fresh culture from this strainer, while the remnants of the flies are caught in the flour strainer and the process can be repeated. Here’s the two strainers together:


I start the actual fly prep by adding vitamin supplements to a cup.


Mites are dislodged from the flies by dusting, so vitamin powders will help knock any mites loose from seed flies. I then add the flies, swirl, and let stand for a few minutes:


Next I dump my dusted seed flies in the two strainer setup:


Now the seed flies are trapped in the upper strainer while some fall through with any mites into the flour strainer:


Finally I dump flies into the culture and seal the top:


Wait 10 days for Drosophila melanogaster, or 14 days for Drosophila hydei and you have a nicely producing culture that is pretty close to mite free!


Types of flies (2017 update)

There are a variety of types of feeder flies that are commonly kept within the hobby. I’ve documented my experiences with the types of flies I have kept. There are other types of feeder flies in the hobby, so this is by no means a comprehensive list.

Flightless Drosophila melanogaster / Turkish Gliders

Turkish gliders are a type of Drosophila melanogaster fruit fly that has been bred for curly wings which prevent them from flying. They can glide for a short distance, hence their moniker, “gliders”.

This is my go-to fly. First, the local exotics shop cultures turkish gliders. This makes supplementing any drops in production with additional flies easier, since I don’t have to ship. Turkish gliders also sustain their production year round for me better than any other type of feeder fly. Initially I tried to keep a variety of flies to vary the foods I offered to my frogs, but over time I simplified my culturing routine, and augmented my feeder flies with feeder bean beetles. I talk more about my fly rotation below.

Wingless Drosophila melanogaster

I raised wingless Drosophila melanogaster for several years when I started in the hobby. They are a good starter fly since they are slower moving than other feeders because they lack wings and simply crawl. I found them more finicky to raise in the Central Texas climate. Seasonal changes in temperature and humidity led to some variations in culture productivity, which caused me to look for other feeders.

Drosophila hydei

Drosophila hydei are a good feeder for larger frogs. I used them extensively when my early frog collection was dominated by large frogs like Dendrobates tinctorius. However, like wingless Drosophila melanogaster, I found the yields for a given culture varied from season to season, with severe crashes occurring in the spring. I had tried a rotation of 4 Drosophila melanogaster, 4 hydei and 4 golden Drosophila hydei a week. This complex feeding structure exposed me to food shortages when my hydei production crashed. After several consecutive years of food shortages in the spring, I decided to move away from hydei.

Golden Drosophila hydei

Golden Drosophila hydei are a smaller hydei variety that are, well, golden in color. They were another feeder I tried to culture when my collection was dominated by larger frogs. Golden Drosophila hydei production was lower for me than regular hydei and I eventually stopped culturing them. Similar to the Drosophila hydei production issues I mentioned above, golden hydei experienced drops in production in the spring for me, leading me to shift my focus from feeding hydei, golden hydei, and melanogaster to feeding exclusively melanogaster. I eventually dropped all Drosophila hydei and shifted back to Drosophila melanogaster.


How many cultures do I need?

There’s never an easy answer to the question “how many cultures do I need?” There are a few variables that can impact your fly culture count:

  • How many frogs do you have? More frogs eat more flies.
  • What kind of frogs do you have? Bigger frogs eat more flies.
  • What yields are you getting from your current cultures?
  • Have you planned for seasonal variations in yields?
  • Do you want extra cultures on-hand to help out other hobbyists?

As of 2017, I have approximately:

  • 17 adult D. tinctorius
  • 30 adult thumbnail frogs
  • ~20 juvenile frogs at any given time

I make 12 cultures per week for ~70 frogs. At any given time I have 36 Drosophila melanogaster fly cultures in my grow out rack. I also keep another 6 to 8 cultures of bean beetles as a supplemental food for my larger frogs. This allows me to absorb seasonal variations in yields, and it affords me the ability to provide fellow hobbyists that have shortfalls with up to about 2 cultures a week without my frogs going hungry.

For larger frogs, I would plan on supporting 2 to 6 frogs per culture where larger frogs like Robertus requiring much more food than a smaller locale like Lorenzo. I target about 6 to 8 thumbnails per culture. These numbers work for me – you should expect to experiment with your weekly count, yields, and fly types to fine tune your culturing to meet your collection’s needs.


Storage and Rotation (2017 update)

Over the years I’ve modified the way I store and rotate cultures. As of 2017, I am only culturing turkish gliders. I find this particular type of fly to be robust with minimal seasonal changes to culturing yields. By consolidating down to one type of fly I decreased my weekly culture prep time. This also consolidated my physical footprint allocated to cultures.

Storage – bins

I keep a weeks worth of cultures (12 in my case as of 2017) in a Sterilite bin. I drilled a series of holes in the top of the bin to improve air circulation / venting of the cultures. This particular bin can hold 3 rows of 4 cultures. The bins make for easy transport of a week’s worth of cultures to the sink for transfer to feeding cups, or when rotating bins when making new cultures.

Storage – diatomaceous earth

You can see the powdery material in the base of the bin presented in the picture above. It’s a whole lot of diatomaceous earth. I use about an inch of this stuff in the base of the storage bins. This helps me maintain spacing between cultures while killing any mites that try to get into the Sterilite bin, or that attempt to move between cultures. It will also capture any escapees from the cultures should a top not be fastened correctly.

Storage – home built rack

I have three bins allocated to fruit fly culturing. A fourth bin is dedicated to bean beetles. Setting these four bins side by side would consume a large footprint (36 fly cultures and 9 to 12 bean beetle cultures). To improve my storage efficiency I built a culture storage rack that I store on top of our second refrigerator in our laundry room. This keeps the flies up and out of the way, while storing them in one of the more consistent temp / RH in the house.


I use this bin and rack design to simplify my culturing process. The top rack is allocated to bean beetles – their bin is always on top, and I rotate their cultures within that bin on a different cadence than the flies. The second bin from the top is the youngest set of fly cultures, moving to progressively older cultures as you move down the rack. I don’t keep cultures beyond the fourth week (I’ll remove those cultures from the bottom rack and use them for final feedings for a few days before discarding them).

My general process for managing flies is:

  • Remove fly bin2 and fly bin3 from rack.
  • Remove cultures from bin3 – use for feeding and discard.
  • Level DE in bin3, wipe down bin walls and lid with clorox wipes.
  • Remove cultures from bin2 – use as seed flies.
  • Wipe down seed fly cultures with clorox wipes, dry with paper towels.
  • Place seed cultures in bin3, place in slot 4 (bottom) of rack.
  • Level DE in bin2, wipe down bin walls and lid with clorox wipes.
  • Create 12 new cultures using bin2 seed flies.
  • Wipe down seed fly cultures with clorox wipes, dry with paper towels.
  • Place new cultures in bin2.
  • Move bin1 from slot 2 in rack to slot 3. This is now bin2, and will be next week’s seed flies.
  • Place bin2 in slot 2 of the rack, bin2 now becomes bin1 and will culture for 10 days before yielding flies.

I repeat this process every weekend, thus the bin1, bin2 and bin3 fly cultures represent week1, week2, and week3 in my rotation, moving down the rack from slot2, to slot3, to slot4 as they age through the culturing process.

I used to try and rotate within bins, but that was difficult and despite my best efforts, led to cross contamination with mites moving from older cultures to newer cultures within a bin. Despite the presence of DE, a culture with a booming population of mites can generate enough mites to create a mite carcass bridge across the DE from one culture to another. Keeping cultures of the same age in different bins makes this mite migration far more difficult.

I find this bin rotation method simple, and it keeps my process consistent from week to week. It also helps if I forget to label a culture with a date, as all the cultures within a bin are from the same week, and they are stacked in order of newest to oldest from top to bottom.


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