A genuine, sometimes tentative, sign of spring in the Cedarburg Bog is the reappearance of dragonflies, but the first sightings may not be of local individuals. Common Green Darners migrate south in fall and repopulate the north country each spring. The Green Darners that deliver the spring lay eggs that hatch into naiads that take the whole summer to mature. These offspring will make the trip south in fall. Chalk-fronted Corporals are northern dragonflies that emerge in early May.