The following recipe is the one currently used by the Biemar Lab at Temple University. It is originally from Laurie Tomkins. Each liter of food contains 5.44 gr of Agar, 9.8 gr of Yeast, 67.5 gr. of Corn Meal, 824,8 ml of Water, 82,9 ml of Caro Syrup, and 4.7 ml of Propionic acid. This recipe makes about 11 liters of food, enough to fill about 6-7 flats of vials or 4-5 flats of vials with 1-2 flats of bottles.
- Agar (Sigma, cat#A1296-5KG).
- Corn Syrup Light (SciMart, cat#DR-807-4).
- Cornmeal Yellow (SciMart, cat#DR-810-50LB).
- Propionic acid (Sigma, cat#P1386-500).
- Yeast Brewers (Sigma, cat#YBD-5KG).
- Mix 59.8 gr. of agar in 6,258 ml of water in the LARGE POT and bring to boil.
- In the SMALL POT, add 107.8 gr. of yeast; 743 gr. of cornmeal; 1,515 ml of waterand stir well.
- Once the large pot is boiling, transfer the content of the small pot and stir well.
- Add 912 ml of Corn Syrup.
- Use 1,000 ml of water to rinse (1) the cylinder you used for the corn syrup, then (2) the small pot. Add this to the large pot.
- Mix well and bring to boil again. Let it boil for 4 min. will still stirring (! This is important; failing to do that will result in burned material at the bottom of the pot).
- Turn the flame off and let it settle for 5 min.
- Add 51.7 ml of propionic acid.
- Mix well and pour the food (use the DrosoFiller for the flats of vials)
- Cover all flats and bottles with paper towels and let cool down for 4-6 hours.
- Plug everything and let it settle at room temperature overnight. Transfer to the cold room the next day.
The food will keep for a month if well sealed, although weaker stocks will do better on food less than a week old. If stored at 4ºC you may find that it 'weeps' when brought to room temperature. You can use these vials but be careful when placing your flies inside. For the bottles though, do not use them if the food seems to be coming of; you will loose all your flies when trying to collect them. Guaranteed.