Silkworms (Bombyx mori) are worms that originate from China or Iran. They are normally 1/2 inch to 3 inches in length.
5 - 10 degrees C in your refrigerator.
If keeping in the fridge, keep them in a plastic container with holes in it, for air. The silkworms will slow down, and go into a slight hibernation. They can be kept in the fridge for up to 1 week. If keeping out of the fridge, and if they have food everyday, the silkworms can live for much longer. They will keep growing though, so feed them to your lizard when their size is just right.