He is best known for his studies of Hemiptera, especially the two-volume work Die Rhynchoten Livlands in systematischer Folge beschrieben ("The Hemiptera of Livonia, Described In Systematic Order").
In 1860 Gustav Flor described a bug he found in Estonia and named it Capsus geminus.
Gustav Mahler | Gustav Klimt | Gustav Holst | Gustav III of Sweden | Gustav I of Sweden | Gustav Meyrink | Friedrich Gustav Jakob Henle | Gustav Stresemann | Roger de Flor | Gustav Noske | Gustav III | Gustav, Hereditary Prince of Sayn-Wittgenstein-Berleburg | Gustav Fischer | Hurricane Gustav | Gustav Nossal | Gustav Meier | Gustav Hertzberg | Gustav Albrecht, 5th Prince of Sayn-Wittgenstein-Berleburg | Johann Gustav Droysen | Heinrich Gustav Magnus | Gustav Stickley | Gustav Krupp von Bohlen und Halbach | Gustav Horn, Count of Pori | Gustav Fröhlich | Gustav Fechner | Gustav Adolfs torg | Gustav | Charles X Gustav of Sweden | Sweden's King Gustav III | Peter Gustav Lejeune Dirichlet |