Culturing Flightless Fruit Flies
(Drosophila melanogaster & Drosophila hydei)
by
David Doyle
01/30/01 (last update 10/12/2002)

This page has the following information:

• Introduction

• Media

• Establishing Cultures

• Number of Cultures

• Temperature Range

• Bacterial Infections

• Mites

• Mold

• Feeding

• Preventing Escapes

• Cleaning Cultures

INTRODUCTION
D. melanogaster & D. hydei are both flightless fruit flies that are the staple of the dart frog hobbyist.  D. melanogaster is lighter in color and smaller, being 1/10 inch (2.5 mm) in size.  At 70 F (21 C) the flies will reach adulthood in approximately 14 days; eight days in the egg and larval stages, and six in the pupa stage.  An adult female can lay 500 eggs in 10 days. D. hydei is darker in color and has red eyes.  The size of D. hydei is approximately  1/8 inch (3.5 mm).  The maturation period is approximately 28 days.

MEDIA
As the name states, fruit flies can be cultured on fruit.  Most of us have had a culture going in the kitchen when we have forgotten about some old bananas.  These are the ones with complete wings and can fly.  DO NOT I repeat, DO NOT culture wild flying fruit flies.  They will get loose from cultures and out of the vivariums and will fly up your nose when you are eating dinner.  If you live with anyone, they will throw you and your flies out of the house.

There are numerous media recipes and all work with varying degrees of success.  The most commonly used medium.  The media is mixed by mixing ½ media with ½ water.  You can reach Carolina Biological at 800-334-5551 / www.carolina.com  The item number is
AA-17-3200  1 liter bag   $   4.95
AA-17-3202   4 liter bag  $ 14.35
AA-17-3204  4 x 4 liter bags $ 56.50

I normally use 1/3 cup of media mixed with 1/3 cup of water in a quart jar.  This results in a cost of approximately $0.31 per culture.

If you need to do conversion from cups to ml or anything similar to that, try the CONVERSION PROGRAM - http://www.joshmadison.com/software.
But for now 1 tablespoon = 3 teaspoons = 14.8 ml = 1/16 cups  and 1 oz = 28.35 grams

Below are some home made media mixes.

Home made "Carolina Mix"      I now sell this mix.  Click Here for more info.
by Christina Hanson

Sift the powdered sugar and the Methyl paraben into a gallon or larger ziplock bag or container.
Shake well.

Add brewer yeast and shake again.

Add the potato flakes and brewers yeast to the ziplock bag and shake well.

Use the same amount as the Carolina Biological Mixture.  I normally use 1/3 to 1/2 cups of media mixed with equal amounts of hot water in a quart jar. This is the media I most frequently use.
The cost is approx. $0.08 per culture

Note:
Methyl paraben, also called Tegosept is a mold inhibitor.  It can be purchased from Carolina Biological 800-334-5551 / www.carolina.com.  The following are the catalog numbers, amounts, and prices.
ba-87-6161  -    30g  -  $7.25
ba-87-6163  -  100g  -  $14.50
ba-87-6165  -  500g   -  $28.50

Banana and Apple Sauce Mix
by Anthony Hundt

1 cup banana (about 2 bananas)
1 cup apple sauce
1/8 cup vinegar (or 2 tablespoons or 15 ml)
2 cups oatmeal
a few granules of baker's yeast

Put banana and apple sauce in blender or bowl and mix until the banana is liquified. Heat in the microwave for approximately 2 min. or until hot enough to kill off any wild fruit fly eggs that were in the bananas, and to reduce mold.  Add the vinegar and mix in oatmeal until it becomes firm, but still moist. Put the mixture in wide mouth quart canning jars and allow to cool.  Once cooled, add the yeast and flies.  Any unused media can be frozen until needed.

Makes approx. 6 quart jar cultures at a cost of $0.18 per culture

The "Power Mix"
By Chis Miller

The following was posted by Chris Miller of Littleton Co on FrogNet on May 8, 2000.

I have been using a mixture of potato flakes, sugar, and Fleischman's activated yeast for years now.  But, after adding a lot of mouths to feed to my collection, I had decided I was going to have to find something that made a lot more flies per jar.  With input from a lot of different sources (Dave and Erin, Tracy Hicks, Jutti,) etc , I have composed a mush that has QUADRUPLED
my fly production.  I have had very little problem with mold, and the cultures seem to last for at least a month or longer.

In a pot bring the following to a boil.
2 cups water
2 cups vinegar
1/8th cup Dark molasses
1/2 can of grape juice concentrate
2-3 overripe mushed up bananas

After bringing this mixture to a boil, add the dry material

1/2 cup malt of meal
2/3 cup potato flakes
1/3 cup Brewers Yeast (the key ingredient)

Place about 2 inches of medium in each qt size jar, and sprinkle maybe an 1/8th teaspoon of activated yeast on the top.  A day later, 20-30 flies are added.  I have tried this medium with my hydei and melanogaster and I can't believe how many larvae are swarming the sided of the jar, I literally can't see through the glass jar, they cover every square inch of glass.  For the first 10 days, I keep the cultures in cardboard boxes which are kept closed, after that, I keep them on a large shelf to help the larvae dry out.

Carolina Drosophia Manual Mix
from the Carolina Drosophia Manual
750 ml water
1-2g (1 level teaspoon) Tegosept (methylparaben)
15g (1/4 cup and 2 tablespoons) Agar (available at health food stores)
130 ml Molasses (sulfur-free)
100g (1/2 cup & 2 tablespoons) yellow cornmeal

Dissolve 15 g of agar and 1 - 2 g of tegosept in 500 ml of boiling water.  To this add 130 ml of molasses.  Be careful not to let this mixture boil over.  Mix 100 g of cornmeal with 250 ml of cold water and pour into the boiling mix. and cook for a few minutes.  While the mixture is still thin enough to pour, pour 2 - 3 cm into the jars.  After this has cooled, add some fiberglass screen to give the flies a place to climb.  Allow this to cool for a few hours before adding flies and a couple granules of baker's yeast.  Cover the jar with a paper towel folded 4 ways then place the lid with holes punched into it over the paper towel.

Make approx. 8 quart jar cultures at a cost of $0.45 per culture

I tried this mix twice and did not have good luck.

"Raising Fruit Flies", Nancy Nehring
Reptiles Magazine, October 1995, pp. 26-28, 30

1 cup water
1 tablespoon cornmeal
1 teaspoon powdered agar (available at health food stores)
1 tablespoon molasses
1/8 teaspoon calcium proprionate (an optional mold inhibitor used in bread.)
1 package bakers yeast

Mix all ingredients except yeast, then heat until boiling. Quickly pour 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 granules of baker's yeast on the surface and add fruit flies.

"Mailbag: Raising Fruit Flies", Dr. Floyd Waddle
Reptiles Magazine, February 1996, pp. 4, 6
1 part brewer's yeast
10 parts instant potato flakes
baker's yeast
Methylparaben mold inhibitor (also know as tegosept)
        Carolina Biological catalog # AA-87-6161 for 1 oz $6.90 or AA-87-6163 for 4 oz $13.90

To prepare dry culture media, mix 1 part brewer's to 10 parts instant potato flakes by weight. When ready for use, mix 4 grams of the mold inhibitor, tegosept (methylparaben), to 1 gallon of hot water and  let cool.  To prepare media add an equal amount of water to the dry culture media (by volume). When the mixture solidifies, add a couple of granules of baker's yeast to the surface and add fruit flies. Calcium proprionate may be used as a substitute for tegosept.  From what most people know, this is the mix used in the Carolina Media.

The following mix was posted by Don Wells on FrogNet

1 liter water
10 grams powdered agar (available at health food stores)
50 grams Farina Cereal ( Cream of Wheat, Baby Cereal or Cornmeal seems to suffice)
100 grams of dry malt (available at home brewing stores)
15 grams dry Bakers Yeast
25 grams of Methylparaben (see note above) mixed into 500 milliliters of 96% proof non denatured alcohol (i.e.,voka)
7 grams of Calcium Proprionate.
_____________________
1. Mix farina( other cereal substitute) malt, agar in a kettle and pour in water.
2. Stir constantly and bring to a boil / simmer for 5 minutes.
3. Stir in Yeast and bring back to a beginning boil.  I also add at this time Spirulina and Klamath        lake Blue Green Algae (Apzomenon flos-aquae (sp?). Usually a teaspoon of each and stir it in well.  You can avoid this if you want it makes no difference with the consistency of the mix.
4. Take from heat pour in 25 milliliters of Methyl Paraben/Alcohol and calcium proprionate and mix well.  Immediately pour into sterile bottles or vials.  Do not allow to cool or it will be hard to pour.  It should not be too watery at this point either.  If it seems watery add a bit more agar and cereal and bring to a boil once more.  I usually try to pour in about an inch and a half of media per bottle.
5. Allow the surface to dry before introducing the flies.  I usually allow it to sit overnight.
6. I put in about twenty five to forty flies per culture bottle. I use glass canning jars usually pint size.

ESTABLISHING CULTURES
First select the culturing container.  Wide mouth quart canning jars with nail holes in the lid are ideal for this purpose. An alternative is to use quart deli cups that have holes cut in the top.  Next, place enough media in the container so there will be between 1/2 and 1 inches in the bottom.  For the Carolina biological media and the home made carolina media, use 1/2 to 1/3 cups of the media for a quart jar and equal parts hot water and sake the container so that all the media is wet. After the media is mixed up and in the bottom of the container, cover the jar with a folded paper towel and place the lid then the ring over the towel.  Allow the culture to cool.  Then add a few grain of baking yeast and spray with a fine mist (just a little water) to hydrate the yeast.  Now place a piece of fiberglass window screen in the jar, this will allow additional area for the larva to climb to and morph.  You can add the flies now or wait a day.  Then add some flies from another culture. 

Shin Sugiyama posted the following on FrogNet regarding establishing hydei cultures:
"I was at a Drosophila research meeting last week and got some tips on keeping D. hydei. One of the problems seems to be that male adult  hydei take a least a week after enclosing to become sexually mature.  Because the females don't take so long , what you do is mix old males (+10 days) with new females to get good egg production.  To do this efficiently just  mix old and new flies."

For places to order supplies and starter cultures Click Here
 

NUMBER OF CULTURES
The more the better!!!  A good rule of thumb is 1 culture per every 2 to 4 frogs with a minimal of 3 cultures per week.  Cultures will occasionally not take or will crash for no reason, so it best to have more than you will need.  Once you have been doing it for a while, you will be able to judge the number you need.  I personally set up 7 - 14 quart jars a week.

TEMPERATURE RANGE
68° F to 80° ;F (20° C to 27° C) but it is better to keep the cultures in the lower portion of the range as at higher temperatures there are more problems with bacteria, fungi, and mites.

BACTERIAL INFECTIONS
A gray or yellow-green sheen (slime) or black dust (the black death) on the media is evidence of a bacterial infection.  Discard the culture at once.

MITES
Cultures can become infested with mites which appear as small white or red bugs.  Any cultures that mites are found in should be immediately disposed of.  Cultures become susceptible to infection once the production starts to reduce.  For this reason, once cultures start to lose their productivity (normally 6-8 weeks), they should be disposed of.  If a mite infection is discovered, remove the infested cultures and store the remaining cultures on paper treated with lidane.  This will act as an insecticide.  I have been told that sometimes you can find this paper in the store but I have not looked.  An alternative to the insecticide paper is to store the cultures in a shallow pan with water in it.

MOLD
Don't worry, you will get some mold every now and then.  Especially if you use one of the homemade mixes.  As long as it is a green or blue mold like what I normally see on fruit and the culture is not solid with it, I normally don't worry and feed from it.  You can lower the amount of mold by using a mold inhibitor such as methylparaben (also know as tegosept) which can be purchased from Carolina Biological.  Another alternative is the use of vinegar to acidify the media and thereby reduce the mold.  All work with varying amounts of success.  What works great for one person may not work for another so just keep trying.

FEEDING
Feed by first tapping the culture on the top of the culture to force the flies to the bottom.  Remove the cover and tap the flies into a plastic bag with dust.  If you are going to be gone for a few days, just remove the paper towel and replace the lid and place the culture in the vivariums.  I normally wrap the culture in a wet paper towel to prevent the frogs from seeing the flies and trying to feed through the glass.  A slice of fruit such as apple can be added to the setup to give a place for the flies to gather, helping the animals to find the food.

How many to feed??   The following are some general guidelines but the amounts will vary depending on the size, number, and species of the animal and the size of the enclosure.  For each froglet in a small enclosure (less than 10 galls) feed approx:
10 D. melanogaster (small fruit flies) or 5 - 7 D. hydei (large fruit flies).  Do this once a day and if there are insects left in the enclosure the next day, reduce the amount fed. If there are no insects left, the next day increase the amounts.  If the animals are adults or subadults double these amounts.  Also the larger the enclosure, the more food will need to be fed.

A piece of fruit such as a small wedge of apple can be placed in the enclosure to attract the flies.  By doing this, the insects will go to the fruit and leave the animals alone.

PREVENTING ESCAPES
To prevent escapes from the cultures, apply a film of petroleum jelly along the top of the culture or store the cultures in a pan or container with water in it.

To prevent escapes from the vivarium.
1)  Put a slice of fruit in the tank that will attract the flies.  Bananas work great.  This keeps them in and helps the frogs find them to eat.
2) Use tight covers and use fine screen or fabric in ventilation areas.
3)  Place containers of water near the tank or on top.  The flies will go to the water and drown if they get out of the tank.
4)  Keep small day geckos in the tanks.  They will feed on the flies that make it to the top of the tank.
5)  Keep the fruit fly cultures in a plastic box with about 1/2 inch of water in it.  Any flies that get out drown and this keeps mites from getting in cultures.
6)  Feed flour beetle larva.  They don't get out of the tank.

CLEANING CULTURES
If the containers are reused, they should be cleaned between each use.  This is best done outside.  First, fill the container with water and allow to set for a day.  After the container has set, dump the container and wash out with a garden hose.  Use a brush to remove anything left in the jar.  Soak the jars and lids for at least 5 minutes in a mixture of approximately 1:20 of household bleach and water.  Rinse the containers well with water and allow them to dry.

Sources of information:
Carolina Drosophila Manual by Carolina Biological Supply Company
Eat This Bug by  Lynn Davis ISBN 0-9653044-0-X
The Dendrobatid Frog Page - FrogNet