Orthetrum glaucum, the Common Blue Skimmer or Blue Marsh Hawk, are dragonflies in the Libellulidae family. The family include skimmers, darters and perchers. The compound eyes are large and meet in the centre of the head. Dragonflies are often found in still water bodies like ponds and marshes. They are carnivorous and help keep insect pest numbers under control. Mosquitoes and midges are often featured on dragonfly menus but butterflies, moths, flies, bees and other dragonflies are also included.
Soh Kam Yung documented a mating pair at Upper Seletar Reservoir Park on 13 March 2022. The male is resting on a small twig just above the water. It has greenish-blue compound eyes and a dark blue thorax. The abdomen is light blue with the last two segments in a darker shade. The female, with light brown splotches on its abdomen, has curled its abdomen upwards to join with the secondary genitalia of the male (under second abdominal segment) so that copulation can take place. The male claspers grasp the female behind the eyes and the pair has formed a tandem link.