Just like butterflies, there are four stages (a complete metamorphosis) in a beetle's life:
Egg— Beetle eggs are usually soft and smooth. They can be laid in the soil, in wood, under tree bark, on leaves, or in carcasses. Depending on the species, a female may lay a single egg (like chafers, Scarabaeidae family) or a batch of several thousand (such as oil beetles, Meloidae family). Most females do not take care of the eggs once they are laid.
Larva— Looking like worms or caterpillars, beetle larvae hatch from eggs. They are sometimes called grubs at this stage. Most beetle larvae have from one to six simple eyes on each side of the head and mouthparts for eating. They eat and grow, molting as they get bigger and bigger.
Pupa— At the end of the larval stage, the grubs either create a pupation cell or find a safe place to go to protect their body during the change. For example, scarabs form their protective cell out of soil, wood particles, and their own saliva; diving beetles burrow into the bank of a water source; many species of wood boring beetles just stop eating and pupate within their own feeding tunnels. Beetles that go through a pupal stage develop the adult legs, wings, antennae, and reproductive system. However, a few beetle families skip the entire pupal stage and keep the features of the larva!
Adult— When the adult beetle emerges from the pupal stage, its body is soft and pale. Soon, the body covering becomes hard, and the beetle's true colors appear. The hind wings and elytra push to the outside of the body.