Nothing really thrives on one food type, it’s good to have a variety. At the very least 2 kinds of insects should be offered. Mealworms are considered treats because they’re high in fat and they’re not all that great so I definitely wouldn’t see a scorpion surviving long-term on mealworms solely. They would do really well off staple feeders like crickets and dubia roaches (or discoid roaches. Dubia are illegal in some states).