This Gray Cracker Hamadryas februa was at the National Butterfly Center, Mission, Hidalgo county, on November 08, 2017. NOTE that it has a small white spot in the center of the black rectangle on the underside of the left forewing, just below the row of four large white such spots. The equivalent black patch on the right forewing lacks a white spot. Glaucous Cracker has a large white spot in this black rectangle on ventral side of both forewings, and also shows the same pure white large spot at this location from above:
