From David Wright via the PALepsOdes listserv comes this timely and interesting tip on how to distinguish the caterpillars of Appalachian Azure (which uses Black Cohosh exclusively as a food plant) and Summer Azure (which also uses Black Cohosh in addition to practically anything else in bloom). David’s pics attached; ignore the crescent as it was part of an earlier conversation.
Appalachian Azures have been flying since before Memorial Day in the wooded state gamelands here in Montgomery County, PA. Today you can find eggs and immature larvae on unopened floral buds of Black Cohosh. Note the yellow first instar near the bottom of the photo. Several weeks later in early July, Summer Azures will use the same host; their first instar is green.