What is metamorphosis?
Metamorphosis is the process by which an insect develops and changes from their larval / nymph stage to their adult stage.
There are three kinds of metamorphosis:
Ametabolism
Ametabolism is a type of life cycle where there is very little actual metamorphosis – only a gradual increase in size. Present only in primitive wingless insects like this silverfish.
Thysanura - silverfish
Hemimetabolism
Hemimetabolism is also known as incomplete metamorphosis.
It is the mode of development in certain insects, like this Squash Bug, that includes three life stages:
Hemiptera - Squash Bug (Anasa trysts)
There is no pupal stage and the insect only goes through gradual changes as it grows in size. The nymph stages often looks much like the adult stage but without the wings or sex organs.
Remember:
Only adult insects (but NOT ALL adult insects) have wings.
Immature insects NEVER have wings (well, there is kind of one exception - mayflies have a subimago stage between nymph and adult [imago] stages that has wings but it they are not sexually mature. They are not in that stage for long, so there is no need to overcomplicate this right now. :D)
Holometabolism
Holometabolism is also known as complete metamorphosis.
It is the mode of development in certain insects, like this butterfly, that includes four life stages:
Lepidoptera - Painted Lady Butterfly (Vanessa cardui)
All immature stages look very different from the adult stage.The morphology and behavior of each stage is adapted for different niches and activities.