1. Tap the bottom of a bottle or a vial on the bench to shake flies away from the plug.

2. Remove the plug rapidly and invert the old culture over a fresh vessel.

3. Transfer some adult flies to the new vessel by gentle tapping.

4. Separate the two vessels quickly, shake flies to the bottom, and replug both.

5. Stocks kept at room temperature (25 °C) should be transferred every 20 to 30 days. Stocks kept at lower temperature can be transferred less frequently.