This freshly emerged Giant Swallowtail is resting in captivity near its chrysalis, in which it overwintered in the Fermilab woods.  I found the chrysalis in the autumn of 2002 in the Fermilab woods and left it in place there for the winter.  The photograph below shows the chrysalis in March.  I removed the chrysalis to a rearing cage on May 11, 2003, but still kept it outside.  On May 29, this butterfly emerged, but its wings never quite fully expanded, hence the curled appearance.  

Like all our Illinois Swallowtails, Giant Swallowtails overwinter in the chrysalis. However, there is some inconsistency in the butterfly field guides regarding whether Giant Swallowtails overwinter this far north.  This Giant Swallowtail chrysalis survived a slightly cooler than average winter (an especially cold February) in northeastern Illinois in the woods at Fermilab. I often see fresh-looking Giant Swallowtails in late May or early June, not only around the Fermilab woods but also in southern Wisconsin.  Although there may be some dispersal to the north each year, I am sure that many of these have locally overwintered.