The mulberry leaves arrived fine, sealed in a plastic bag. The first time I ordered them, I fed one to the silkworms and kept the bag sealed. The remaining leaves developed a fungus within a day or two.
This second order, I kept the bag unsealed and there was no fungus problem. I don't know if keeping them in the sealed plastic bag caused the fungus problem. I couldn't find any information about how best to store mulberry leaves.
The main thing about the leaves is that you need to order quite a number if you want the silkworms to get big. They eat voraciously. If you plan to feed them to your reptile while they're still relatively small, then you'll be fine with 5 or 10 leaves. If you run out of leaves, the silkworms starve pretty quickly, so you need to use them (the silkworms) or lose them.