Fruit flies are not fussy. In fact you will probably find them living on all sorts of things - old fruit, cereals, bread etc. However, when we culture flies we need to be provide food for both adults and larvae, and it has to be a food that is long lasting, and of a suitable consistancy to remain in place when the fly containers are inverted. I use the Sussex mix, but have included two commonly used recipes. This will feed the larvae, but not the flies - all food should be sprinkled with brewers yeast for the adult flies. Not only does this provide a source of food for the flies, but also ensures the surface is dry, and the delicate flies will not get stuck down to sticky media.
- Banana - Bunch of bananas, 1/2 cup sugar, packet of oats, 1 packet bakers yeast. Blend it all together! Mold inhibitors if available
- Potato - 1 part bakers yeast to 10 parts mash potato mix. Add hot water! Mold inhibitors if available
- Sussex Mix - Add 100g maize meal to 95g sugar (or molasses), 6g agar, 19g bakers yeast to 1 litre of water. Bring to the boil stirring from time to time. This mix must boil for several minutes to activate the agar. Leave to cool for a while and then stir in 2g Nipagin (methylparaben) or perhaps try tegosept or calcium propionate (mold inhibitor used in bread) and any vitamins (I use dog multivitamins).
I strongly recommend the Sussex mix. It is long lasting, solid enough to stay in its vial when tapped upside down, and meets all the nutritional needs of the larvae.
Whichever media you use, you will need to store it either in small vials that you will keep the flies in, or in a larger container that the media can be decanted from.