Sachem is more common to the south of Chicago.  It probably does not survive the winters this far north but often disperses north by late summer.  This specimen is probably a male.  The female's markings are more nearly white and distinct, as can be seen below.  

Sachem may be the most common skipper in suburban backyards in Oklahoma.  Since this photo is sharper than that of the local specimen, I include it even though it was taken outside of the Chicago area.