Darkling Beetle Life Cycle

These are my normal mealworms.

The initial appearance of the pupa is creamy white. The colour darkens over time.

A Darkling beetle in the final stage of Metamorphosis

The above are my Darkling beetle. On the left is a newly emerged Darkling Beetle, it's light creamy white and the wings are still wet. After a few hours, it will gradually turn brown. After a day or two it will turn completely black like the beetle in the middle.

Complete Metamorphosis
Mealworms are the larvae of Darkling beetles.
The Darkling beetle has four stages in its life cycle.
The four stags are egg >> larva >>  pupa >> adult.
These four stages indicate a complete metamorphosis.