Adult male azure damselflies have a head and thorax patterned with blue and black.

(This distinguishes it from the variable damselfly where the U-shape is joined to the terminal band with a black line.)

Adult female azure damselflies have a head and thorax pattern similar to that of the male, but with glittering, glossy green replacing the blue colouring.

They develop in one year (two in the north), feeding among submerged vegetation and on small invertebrates.

The behaviour is also different - unlike common blues, they rarely fly out over large stretches of water.