Fully green, no dark markings on pronotum. Compare black marks on antenna bases to diagrams at SINA and pictures at BugGuide. They are bold and may be large enough to touch each other.
SINA: https://orthsoc.org/sina/581a.htm
This species should occur statewide but has not been reported in iNaturalist. BugGuide has some records. It was included in Knutson and Jaques (1935) list as Oecanthus nigricornis argentinus.
Occurs in vegetation from prairies to shrubs. Does not occur in trees.