A Black Swallowtail butterfly (Papilio polixenes) nectaring on a Basket Flower (Centaurea americana). One of the largest butterflies that we see in Texas. Similar in size to the Monarch. The wings of the females have blue bands of color on them while the upper surface of the male wings will lack this band. Many species are sexually dimorphic, which is a fancy way of saying the sexes look different from one another in some way(s). I am continually amazed at the way they use their proboscis to find the tiniest florets on a compound flower like Centaurea and other Asteracea family members.