Development with complete transformation is characteristic of caddis flies. What stages are typical for them?

Development with complete transformation is characteristic of caddis flies. What stages are typical for them? Why is it necessary to have different stages of development?

1) an egg, a larva, a pupa, an adult (imago) – stages with complete transformation;
2) the presence of different stages of development is necessary to avoid competition for food resources between the larva and the adult.

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