I believe it was on March 20th that I noticed the colonies of Camponotus castaneus were once again awake. The clusters of brood to both colonies started developing.
As a little nuptial flight update I've been reading reports of Camponotus pennsylvanicus, americanus, and chromaiodes (3 fairly abundant species in North America) have started flying. Time of day is something of an issue though. I believe most species fly in the late afternoon and continue on into the night. Come 11:00pm though and they've stopped flying completely. Queens wonder around for upwards of 24 hours after flying. They're not horribly common in most places but because of their lumbering size (13 to 20mm long) they're easy to spot.