Flightless fruit flies are an easy-to-culture feeder insect for small reptiles and amphibians. They can be purchased from reptile supply and biological supply companies as well as some specialty pet stores. There are two common species available. They are Drosophila melanogaster and Drosophila hydei. The main differences between the two species are the adult size of the fly and the time that the flies take to go through their life cycle. D. hydei is the larger of the two with adult flies generally measuring around 1/8 inch (3 mm), while D. melanogaster matures to a smaller size of around 1/16 inch (1.5 mm). D. melanogaster takes roughly two weeks (depending on temperature that cultures are kept at and medium used) to go from egg to maggot to adult fly and the newly morphed flies can reproduce after 24 hours. D. hydei develops slower and takes roughly one month to go through its life cycle. D. melanogaster is commonly available in two separate mutations: flightless and wingless. The flightless variety has wings but they are vestigial and can not fly.

I have been culturing the flightless variety of D. melanogaster for over six years now. All of the techniques for culturing fruit flies on this page are methods that I have used. I have heard that they will also work for culturing D. hydei but I have not tried these methods with that species myself.

The Container

The container that fruit flies are cultured in has to be escape proof but also ventilated. I have used a number of different types of containers to culture fruit flies in. I started culturing fruit flies in mason jars with paper towels screwed down on top for ventilation. These worked well but were expensive to buy, hard to clean, and the paper towel on top would often break resulting in 1000’s of fruit flies escaping and roaming through my bedroom (not a pleasant experience). I later switched to using empty Snapple bottles plugged with cotton. Once again, these were hard to clean and not always escape-proof, so I switched to using plastic 24 oz. or 32 oz. deli containers. I cut a hole in the plastic cover, placed a paper towel over the culture and then secured the cover back on the container over the paper towel. I used this type of container for years until I discovered special 24 oz. plastic containers designed specifically for keeping insects in. These containers come with pre-drilled holes that are covered with a thin paper. They are escape proof, ventilated well, and are easy to clean so they can be reused. They are available from some of the websites at the bottom of this page.

The Medium

The medium is what goes into the bottom of the container and serves as food for both the larvae and the adult flies. It can be purchased from both biological supply companies and some specialty reptile supply stores, or you can choose to make your own. In general, commercially available mediums do not yield as many flies as a well-made medium from raw ingredients. Making your own medium is the way that I prefer because I get more flies from each culture and it is much less expensive. Below are the two homemade mediums that I have used with good results. You can modify and experiment with them to see if anything increases the amount of flies that are produced. I did not come up with or create either of these.

The "Harvey Peterson Medium"

Add the following ingredients to standard 24 oz. or 32 oz. deli containers or insect cups:

½ cup of warm water
½ tablespoon of white sugar
1 tablespoon of powdered milk
4-6 tablespoons of instant mashed potatoes
5-15 granules of baker’s yeast

First dissolve the sugar into the warm water. Then add the powdered milk and stir well. Add the instant mashed potatoes. The amount of instant potatoes that you add will depend on the humidity level where the cultures are stored and how well the cultures are ventilated. Not enough instant potatoes and the medium will be too wet and you won’t be able to successfully remove flies from the culture. If you add too much instant potatoes and the medium will dry up and the culture will stop producing. I’d recommend starting with only four tablespoons and then increasing from there if needed. After adding the instant mashed potatoes swirl the container around in your hand so that the potatoes mix well with the other ingredients, then let it sit for a few minutes. Once it solidifies sprinkle the baker’s yeast on top and then add 25-50 fruit flies. Alternatively, the dry ingredients can be mixed together in a large bag in the same proportions as above and mixed in containers with equal parts water and medium. This strategy works well if you are making a large amount of cultures.

The "Power Mix Medium"

In three separate containers...

Boil:
1 mushed banana
½ can of grape juice concentrate
14 oz. of applesauce (half of a large jar)
1/8 cup of molasses

Combine:
1 cup of instant mashed potatoes
½ cup of brewers yeast

Combine:
1 cup of water
1 cup of vinegar

Once the boiled mix has cooled to a reasonable temperature add 6 tablespoons of it to a standard 24 oz. or 32 oz. plastic container. Then add 6 tablespoons of the dry mix and then 2-4 tablespoons of the water/vinegar mix and stir very well. The amount of water/vinegar mix that is added will depend on the humidity where the cultures are kept and how ventilated the containers are. Let it all sit for a few minutes until it solidifies and add 25-50 fruit flies. I find that this medium produces extremely high yields of very large, healthy flies. Unfortunately, it is not easy to make and takes more time to setup cultures that the Harvey Peterson medium mentioned above.

Additional Information

- Store the cultures in an area where the temperature does not fall below 70F (21C) or rise above 85F (29C). The flies will go through their life stages faster when kept at higher temperatures and slower when kept at lower temperatures.

- You can significantly increase the amount of flies that a culture produces and the entire life of the culture by adding extra egg-laying sites to the culture. Fruit flies will lay their eggs on pretty much anything solid. You can sink pieces of cardboard, poster board, or aluminum window screening into the medium to form extra solid egg-laying areas. Of course, if the medium isn’t lasting long enough for the flies to fill up the sides of the container with eggs then there isn’t any need to add additional egg-laying sites for the flies. Excelsior, commonly sold as American moss at craft stores, works very well for creating additional egg-laying sites.

- Do not mix different strains of fruit flies in one culture. The result will be horribly annoying flying fruit flies that have no consideration for you or your comfort. Anyone that has ever accidentally made this mistake won’t make it again.

- When setting up new cultures use flies only from healthy cultures. It can be easy to spread mold and other common problems that can literally wipe out all of your new cultures. Occasionally some of the cultures might not produce very well or at all and because of this I would recommend setting up new cultures weekly whether you need the extra flies or not.

- If mold is noticed in any culture move it to a new area away from the others, or even better throw it away. Mold is a very common problem when culturing fruit flies, but can easily be controlled by always removing moldy cultures as soon as they are noticed.

- Write the date that the culture is setup on the side of the container with a permanent marker or label. The date when a culture is setup with determine when flies can be removed from it and when new cultures can be created from those flies so it's important to keep track of the date when cultures were created.

Using Fruit Flies as Food

Once the first set of flies have gone through their life cycle some of the flies can be removed for food. The best way to remove flies is to gently tap the culture on the side of another empty container. Once the flies are in the empty container they can either be coated with a high quality reptile vitamin and/or calcium supplement or can directly be fed to your hungry animals.