BREEDING VESTIGIAL WINGED ("WINGLESS") FRUIT FLIES
(Drosophila melanogaster)
Fruit flies have several advantages over hatchling crickets as a live food. They stay small, they require no maintenance once a culture's set up and it's cheap and easy to produce astronomical numbers in very little space. The following method is very productive for the vestigial winged ("wingless") strain - less so for the larger, winged, flightless strain.CONTAINERS
I use 7oz (200gm) coffee jars with plastic lids though smaller jars may be just as suitable. A hole can be cut (carefully) in the lid with a sharp craft knife and plain net curtain material glued over the hole. Alternatively, a heated knife can be used to cut the hole with 5cm thick plastic foam to plug it.THE CULTURE MEDIUM
The following ingredients are sufficient for three jars. These ingredients can be increased or reduced proportionately depending on the number of cultures required. Yeast is not necessary and there are no strong unpleasant smells.
- Half a cup of porridge oats.
- One cup of water.
- One tablespoon of black treacle (molasses).
- One "CAMPDEN" tablet (these tablets are used in home brewing to prevent mould formation and can be bought from stores selling home brewing equipment).
- One teaspoon of AGAR (this sets the mixture).
METHOD
- Put the oats and water in a pan and heat the mixture gently until it has a uniform, creamy consistency (ie: porridge).
- Stir in the molasses until, again, the mixture is of uniform consistency.
- Crush the "CAMPDEN" tablet (between a spoon and a plate).
- Stir in the agar.
- Pour the mixture evenly into three jars.
- When the mixture has cooled down and set insert a piece of crumpled greaseproof paper in each jar (to allow the larvae to climb and pupate). Greaseproof paper is more suitable than a porous material such as kitchen towel because it won't absorb moisture from the mixture to the same extent.
- Introduce a maximum of about 20 flies to each jar then store the jars at a temperature of between 21°C and 26°C (70°F and 80°F). Storage at higher temperatures will cause the mixture to dry out and so destroy the culture.
If the jars are stored at a temperature of 25°C (77°F) it takes approximately 19 days from the introduction of the flies to emergence of the next generation. Each jar usually produces at least two generations. Beware of mite infestations. If mites are present in large numbers it's a good idea to set up a new culture.
HANDLING
The flies can simply be tipped out of the jar because the culture medium is solid. Handling can be made easier by inserting a plastic funnel in a suitable container, tipping the flies into it then putting the container in the fridge for a few minutes (to slow the flies down).Finally, a word of warning to the uninitiated. Although the "wingless" strain cannot fly, they do climb to the top of anything in their near vicinity. For this reason it's advisable to prevent escapes. "Rogue" fruit flies on the rampage can be very irritating - especially when you're eating salad!