Am starting this as a photo ID thread of the most common butterflies. Hopefully this will be helpful to newbies! (I have added a link in the first post of the sticky thread.)
I would like to suggest to everyone who wants to add a butterfly to this thread, if they would please reference the BugFile thread. If we get too many photos here, it may get too confusing. If you look at BugFiles and don't see enough photos of a particular butterfly, please add some of yours there (to BugFiles). Especially photos such as eggs, and also first and second instar caterpillar photos.
I will start this thread off with one of my favorites. The Monarch butterfly which can be found just about everywhere in North America! I also consider them the friendliest butterflies and do quite well being hand-raised and released.