How long does it take for caterpillars to be born?

Overwintering eggs hatch early in the season, then the caterpillars start eating like crazy and building their tent. they become fully grown by late spring or summer, and during the growing process they can actually eat every leaf from a tree, so that the tree must redevelop all of its leaves.Once the caterpillars are grown they wander off and hide themselves in well protected places such as a piece of tree bark laying against rock.There they spin silken cocoons for themselves, then moths emerge from those cocoons in a few weeks.