I set up a good size plant pot with different layers. This helps keep the moisture inside the pot. I cover all that with another layer of planting soil, then I place a dozen earhworms inside. I keep my 'pot' in a dark cool place and regularly water it so that the earthworms will have enough moisture. Once a week I dig in a bit and add up some more peelings if needed.
Earthworms are hermaphrodites, just as the aquatic snails.
They grow a batch of eggs at one of their extremes. The entire earthworm production takes about three months. Removing morms from the pot to feed to the turtle can be done in two different ways. This is easier to do if you have a garden. Get a wide opening container.