When does a tiger moth change from a caterpillar to a moth?

In cooler climates like the northeast: early June to early July the adult moth takes flight. In warmer climates there can be two broods. More in very souther climates. Adults emerge from their cocoons in mid morning. Larvae which grow to approx. 3.5 inches are mostly green throughout their five larval stages and spend about one week in each stage except the longer fifth instar (stage). This is all I can contribute at this point.