SV Fruit Fly Medium Recipe
The following recipe is intended to serve as substrate and nutrients for fruit fly larvae. This is the recipe we use for our own fruit flies, but there are plenty of others with different variations on the internet. All the ingredients are readily available for hobbyists in Australia, where we are based. If this recipe doesn't work for you, feel free to try others online! Do let us know if you had troubles with it, we're constantly trying to improve things.
This recipe makes enough mix for multiple cultures. The dry ingredients should be stored in an airtight container in a cool place, and starter ingredients should be added when setting up new cultures.
Notes on Mold and How to avoid it with this recipe:
Mold seems to occur in home made recipe cultures for a variety of environmental reasons. We're experimenting with ingredients to make this occur less often, but for those who keep getting mold- lab grade mixes work best.
Here are my tips to avoid mold in your cultures:
- Maintain your cultures in warmer temperatures. The yeast in the recipe grows best in warm temperatures, mold does better when it is cold. 20-24C is most ideal for both yeast and fruit flies to breed fastest.
- Make sure the mix isn't too dry! The yeast has trouble taking hold if the culture is dry.
- Make sure the mix is made in the order that we've written- the yeast needs to be alive and heating them up in the microwave can kill them! Don't forget to store your extra yeast in the fridge or freezer if you want to reuse them later.
Dry ingredients (mixed together):
- 4 cup of oats
- 1 cup of brewers yeast (inactive)
- 4 teaspoons of cinnamon
This makes a bulk amount that can be stored dry for later.
Starter Ingredients (when setting up a culture):
- 1 tablespoon Dry Ingredients
- 1 light sprinkling of active baker's yeast
- 1 teaspoon of white vinegar (optional)
- 1 or more tablespoons of water
This method uses enough of the ingredients to make substrate for 1 culture (depending on hydration). This cannot be stored and should only be used when planning to set up new cultures soon.
- In a small bowl, put in about 1 tablespoon of the dry ingredient mix and 1 tablespoon of water. More or less may be used to preference.
- It is recommended to microwave the mix (not inside the culture cup) until it starts to boil. Hobbyists do this to kill off some of the possible unwanted fungus and pests that could compete with the flies, and also to hydrate the oats faster.
- Cover and allow the mixture to cool to room temperature before continuing. If the mixture becomes too thick whilst cooling, add a bit of hot water and mix and wait again. Repeat this until the mixture is at the consistency of soft mashed potatoes, but not runny and is at room temperature.
- Stir a very light sprinkle of baker's yeast and a teaspoon of white vinegar into the mixture. This will kick start the fermentation of the mix to feed future fly larvae, and out compete unwanted mold.
- Spoon the mix into the culture cup, taking care to avoid getting the mixture over the sides. The substrate should be about 2cm thick.
- Add the excelsior or shredded paper before shaking in adult flies.