Mealworms are the larval form of the mealworm beetle, Tenebrio molitor, a species of darkling beetle.
Like all holometabolic insects, they go through four life stages: egg, larva, pupa, and adult. Larvae typically measure about 2.5 cm or more, whereas adults are generally between 1.25 and 1.8 cm in length.
Mealworms are edible for humans. Baked or fried mealworms are marketed as a healthful snack food. They may be easily reared on fresh oats, wheat bran or grain, with sliced potato, carrots, or apple as a moisture source. (source)
So can hamsters eat mealworms?
Yes they can as long as they have been bred in captivity and not found in the wild.