There's a butterfly around here that's almost a Monarch, but not quite. That's it above.
You might find it interesting to match that picture with one of a Monarch, maybe in a field guide or on the Internet. Monarch Butterflies are Danaus plexippus. The picture shows DANAUS ERESIMUS ssp. MONTEZUMA, whose English name is Soldier. Because the two species belong to the same genus, Danaus, it's clear that they're closely related. There's another Danaus in Mexico known as the Queen.