The St. Croix Snaketail, Ophiogomphus susbehcha, is a clubtail dragonfly species.  This means it is of the genus Ophiogomphus, and the family Gomphidiae.  The complete classification of the St. Croix Snaketail is as follows:i see you

Domain: Eukarya
        -organisms with true nuclei
Kingdom: Animalia
        -multicellular organisms that do not possess a cell wall
Phylum: Arthropoda
        -organisms with bilateral symmetry and an exoskeleton
    Subphylum: Hexapoda
            -organisms with 3 pairs of legs
Class: Insecta
        -organisms with 3 pairs of legs, a segmented body, and a pair of antennae
    Subclass: Pterygota
            -possess wings
        Infraclass: Palaeoptera
                -winged insects that do not fold their wings over their abdomen
Family: Gomphidae
        -yellow or green body color with black or brown markings
Order: Odonata
        -have an aquatic larval stage in their life cycle
    Suborder: Anisoptera
            -have larger forewings than hind wings
Genus: Ophiogomphus
        -possess green clubbed abdomens with snake-like pattern of white and yellow spots
Species: Ophiogomphus susbehcha (Vogt and Smith, 1993)
S9 has a round spot and S10 is yellow. Additionally, they have grey-blue eyes and black legs.

Taxonomy information credited to Encyclopedia of Life (EOL, 2013), Dragonflies of the World (Silsby, 2001), and Dragonflies through Binoculars: A field guide to Dragonflies of North America (Dunkle, 2000).

The latin root "ophio" means snake-like and "gomph" refers to the wide, club-like distal portion of the dragonfly's tail.  The origin of its common name, St. Croix Snaketail, arose from the discovery of the species in the St. Croix River between Minnesota and Wisconsin (Vogt and Smith, 1993).

Photo Matt Berg