California darner. - Stockfoto

The California darner (Aeshna californica) is a medium-sized dragonfly with a length of 2 1/4 to 2 1/2 inches (57 to 64 mm). The male is dark brown to brownish black. Each side of the thorax is marked with two blue to bluish green diagonal stripes, while the top of the thorax is unmarked. The abdomen is marked with large blue spots alternating with smaller greenish dots. There are several wide blue bands circling the abdomen near where it meets the thorax. Most females resemble the males in color, but some may have greenish yellow markings instead of blue.