There are four stages of in the life cycle of a mealworm: egg, larval, pupa and adult. A mealworm is not the adult version of the bug; a mealworm is the larval stage of an insect that eventually grows into a beetle in the adult phase. The life cycle of mealworm lasts approximately one year.
The first phase of a mealworm's life cycle is the egg phase. A mealworm lays hundreds of white eggs. After four to 19 days, these small white eggs hatch into mealworms, entering the second stage of the insect's life cycle.
During the larval stage small yellow mealworms spend all their time eating. As they grow, they shed their exoskeleton so they can continue to get bigger, much like a snake shedding its skin.
Once the mealworm is big enough it enters the pupa stage. This is a very lazy time during the mealworm's life. The insect does not move or eat during this stage because it is going through a transformation process and developing into an adult beetle. This stage can last anywhere from two weeks to nine months, depending on the time of the year.
After the pupa stage, the insect enters the adult stage, at which point an adult-sized beetle comes out of the pupa shell. At first it is white, but with time the beetle darkens until it eventually becomes black. The adult beetle lives for a series of months and then dies.