Orthetrum coerulescens can reach a body length of . These dragonflies have a
thorax with pale yellow ante-humeral stripes. In the males the color of these stripes fades with age. The abdomen is rather slim and shows an evident dorsal keel. Males have blue-grey eyes and a blue pruinescence on the abdomen, developed with age. Young males are yellow-brown. On the contrary some (
androchrome) females at the end of the reproductive cycle assume the bluish color of the male. In the female the abdomen is yellowish-brown, with a thin median black line and small transverse lines to the connections of the various segments. The hyaline wings have yellow costa and a long yellow-brown
pterostigma (about 4 mm). They are usually hold well forward at rest. This species resembles the
black-tailed skimmer but is smaller and slimmer and the male has no black tip. Females and immature males lack the black
abdominal pattern. File:2014.07.18.-16-Schwarzbach Woellnau--Kleiner Blaupfeil-Maennchen.jpg|Immature male File: Libellulidae - Orthetrum coerulescens - Mature male.JPG|Almost mature male File: Libellulidae - Orthetrum coerulescens-3.JPG|Mature female File: Libellulidae - Orthetrum coerulescens - androchrome female.JPG|
Androchrome female ==Biology and behaviour==