Fruit flies are among the most popular insects to breed in captivity. They are bred for scientific purposes, as food for other pets, or as pets. They are easy to care for and don’t require much space or equipment.
There are several ways how to house and breed fruit flies. Many breeders use special powders or fruit-fly-medium mixes to breed their fruit fly cultures, but it is also possible to use only items and ingredients that you already have at home.
What do Fruit Flies Need to Breed?
Here is a full list of things that you need to breed your own fruit fly cultures:
- The fruit flies you want to breed
- Plastic cup (300 – 600ml) with a lid
- Materials for filling, e.g. paper strips, wood
- Ready to go Media or ingredients to make your own media
You can buy fruit fly cultures in an already set-up container with some media inside. Setting up your own cup with a fruit fly culture is cheaper, but takes more time.
If you are planning to feed the fruit flies to your pet, it might be better to set up your own culture, otherwise, it might get too costly.
If you want to keep one culture of flies as your pets and won’t pursue this hobby afterward, a “ready-to-go” fruit fly culture in a cup might be the right choice for you.
The Fruit Flies You Want to Breed
You can buy the common Drosophila Melanogaster as well as the Drosophila Hydei in many pet shops and also in many online shops.
Shipping live animals is always a risk for the animals. If you have the option, it is better to pick up the flies in a local store, especially during very hot or very cold times.
Many online shops protect their flies during shipment in winter with warm packs, so even if you have no other option than to order them online, they will probably be fine when they arrive at your place.
Plastic Cup (300 – 600ml) With a Lid and Tissues
Prepare the home for the fruit flies by cutting a hole in the lid. Place the tissue between the lid and the cup, so that no fruit fly can escape through the hole in the lid, but they can still get fresh air from outside of the cup.
You can also use glass containers or jars to keep your fruit flies as long as you have a lid. The container needs to be transparent because fruit flies don’t like to be held in complete darkness.
Materials for Filling, e.g. Paper Strips or Wood
Plastic parts, coffee filter paper, paper strips, or wood need to be on top of the media to give the fruit flies a place to sit.
Otherwise, they might drown in the media, once it gets softer from all the larvae and pupae activity.
Ready to go Media or Ingredients to Make Your Own Media
There are several fruit-fly-medias on the market that is mixed with boiling water, stirred, and ready to be used. These media usually lead to great results but tend to be a lot more expensive than making your own media.
The advantage of media that you buy is that it’s less messy, you can use it immediately and thereby save some time, and you can only use it on one or two cups. Pre-made fruit fly media is also usually mixed with some kind of ingredient that prevents mold, while homemade mixtures are prone to molding.
If you want to mix your own media, you should make a bigger amount, otherwise, it’s simply not worth the effort. The downside is the price.
Some good fruit fly media are:
- Formula 4-24® Instant Drosophila Medium
- Repashy SuperFly Fruitfly Culture Medium
Recipes for Your Own Media:
There are plenty of recipes that can be found online for making your own fruit fly medium.
Here are two options for fruit fly medium:
Recipe 1 – Liquid mixture
by Nancy Nehring, Reptiles Magazin, Oct. 1995, pp. 26 – 28, 30
- 1 cup water
- 1 tablespoon cornmeal
- 1 teaspoon powdered agar
- 1 tablespoon molasses
- 1/8 teaspoon calcium propionate (optional)
- 1 package bakers yeast
Mix all ingredients except yeast, then heat until boiling. Quickly pour the mixture into clean culture jars. Cap and let cool to room temperature. This mixture can be stored in the refrigerator with a tightly capped lid until ready for use. When ready to use, sprinkle a couple of granules of baker’s yeast on the surface and add fruit flys. Calcium propionate is a mold inhibitor used in bread.
Recipe 2 – Dry mixture
You can also make a dry mixture that can be stored for the future. Common ingredients are instant mashed potatoes, cornstarch, cinnamon, sugar and yeast.
Here is one recipe for a dry mixture that you can mix with boiling water once you are ready to use it.
- 1 cup Instant mashed potatoes or potato flakes
- 6 tablespoon Cornstarch
- 1 tablespoon Sugar
- ½ table Cinnamon
- Active Baker’s Yeast
Mix the instant mashed potatoes or potato flakes, the cornstarch, the sugar, and the cinnamon in a bowl. You can store this mixture for future usage.
When you are ready to set up a culture, make a layer of around 2cm in your cup and pour some hot water in the medium. Sprinkle a bit of active baker’s yeast into the medium and stir everything until it becomes a homogeneous texture.
Wait until the mixture is cooled off and check the consistency before adding the flies. The flies should not be able to drown in the mixture, it should be hard enough for them to walk on.
Step-by-Step Guide on How to Set Up Fruit Fly Cultures
It is common to set up several fruit fly cultures at once. If you want to feed the fruit flies, you will probably need more than one culture per month. But of course, it is also possible to start with a single fruit fly culture.
- Gather everything you need
- Buy or collect fruit flies
- Prepare the container
- Mix the fruit fly medium
- Place the filling material in the medium
- Add the fruit flies
- Choose a good spot
In the following, I will go into more detail about every step.
Gather Everything You Need
Get all the items together, that you need to set up the new home for your fruit flies: Plastic cup with lid, tissues, materials for filling, and media.
Buy or Collect Fruit Flies
Buy the fruit flies you want to breed or (if you are happy with breeding wild fruit flies) catch some fruit flies in your home or outdoors.
Prepare the Container
Cut a hole in the lid of the cup.
Mix the Fruit Fly Medium
Mix the media according to the package information or according to the recipe on how to make your own media and wait until it is cooled off.
The media should only take up a few centimeters of the bottom of the cup and not fill the container up entirely. Filling the cup up to 15%-20% at the bottom is more than enough.
The fruit fly media serves as food and also as the place where the fruit flies can lay their eggs, and where the freshly hatched fruit fly larvae will take their first few bites to eat.
Always cover the cups with the lids while the media is cooling down. The media might attract wild fruit flies and they can be quick in laying their eggs in your freshly prepared culture.
If you are planning to breed flightless fruit flies, you might be disappointed if you end up with flying, wild fruit flies instead.
Place the Filling Material in the Medium
Place the materials for filling into the media. The media should be hard enough that the filling material doesn’t sink into the media.
The filling material can be any kind of plastic form, paper stripes, wood carvings, etc. It simply has to be some kind of material the fruit flies can sit and crawl.
At some point, the media will become more liquid due to humidity, liquids from the flies, and larvae and pupae in the media so that fruit flies might get stuck in the media and drown if they don’t have another place to sit.
Don’t put the flies in while the medium is still sticky.
Add the Fruit Flies
Now you can add your fruit flies. Hold the tissue and the lid close when you start handling the fruit flies.
If you chose flying fruit flies, you might want to put them in the fridge for a few minutes which will slow them down and make it easier to handle them.
You can also use a product to anesthetize your fruit flies for the duration of moving them to make sure that they don’t escape. “FlyNap®” is a well-known product for that cause.
Especially if you need a bit more time or want to select males and females, anesthetizing your fruit flies might be a good option.
If you own flightless fruit flies, it will be easier to keep them in the cup.
Take the cup with the fruit flies and tap it gently so that all fruit flies fall to the ground. Tap the side of the bottom so that the flies end up in the corner of the cup.
Now remove the lid and pour the fruit flies into their new home by tapping against the cup, making the fruit flies fall into the new container.
Quickly put the tissue on top and close the cup with the lid so that the fruit flies cannot escape.
The fruit flies will start to eat the medium on the bottom of the cup and lay their eggs. After a few days, you will see tiny fruit fly larvae in the medium. After about 2 weeks the larvae will have gone through the pupae stage and reached adulthood.
You should change the fruit fly cup after 30 days to avoid mold, diseases, mites spreading, or overpopulation, depending on how many flies you harvest.
Choose a Good Spot
Place the cup with the fruit flies in a warm and humid spot with no direct sunlight.
The perfect conditions for fruit flies are 70°F – 80°F with a humidity of 60% – 80%. This can be achieved by spraying water into the cup or placing the cup with the flies in a humid place such as the bathroom.
Direct sunlight can heat up the cup very quickly and kill your fruit flies within a few hours, therefore you should choose a place with only indirect light.
How to Feed Fruit Flies
In most cases, fruit flies are bred to be fed to pets.
If you want to harvest your fruit flies, and you own flightless flies, you can tap on the cup to make them fall down to the bottom to avoid them crawling out once the lid is removed.
Keep tapping the cup while you remove the lid if you see them crawling upwards.
Now place your cup directly over or inside of the enclosure of the pet you want to feed and let some flies fall into the enclosure by continuously tapping against the sides.
Put the tissue and lid back on immediately once you are done feeding.
If you own flying flies, you might want to put them in the fridge for a few minutes before opening the lid.
They will become much slower when they are cooled down and you don’t want them to escape and build multiply anywhere else than in your cup.