Its main purpose is to eat as much food as possible and grow as big and strong as it can. When it turns to a butterfly, it is now concerned with finding a mate and it only eats enough to gain energy to flap its wings. This allows each stage to be more efficient in its life cycle than insects that do not undergo metamorphosis. FloridaEnto and Polly-themus both knew the answer to this one. Most insects have 4 wings.
Beetles have thick, armor-like front wings that protect their bodies.
To fly they move these out of the way exposing their thin and flexible hind wings. At rest, you cannot see the hind wings because they are under the forewings. Some ants do have wings, but there two more body features only ants have. Worker wasps have wings, worker ants don't have wings. Also the ant has a raised hump connecting the thorax to the abdomen.