The black-tailed skimmer (Orthetrum cancellatum) is a dragonfly belonging to the family Libellulidae.
This species is widespread in Europe and Asia. It is found throughout European continent including the Mediterranean islands but is absent in the north of Britain and the northern half of Fennoscandia. This is one of the most common European species and it is still increasing its range northwards. To the east, the range extends over central Asia to Kashmir, Mongolia to the northern parts of China and Arunachal Pradesh in India.
It is present in Albania, Austria, Azerbaijan, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, China, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France (Corsica, and mainland), Georgia, Germany, Greece, Hungary, India, Ireland, Italy, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Luxembourg, Malta, Moldova, Mongolia, Montenegro, Netherlands, North Macedonia, Norway, Poland, Portugal, Romania, Russia, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Tajikistan, Turkey (Turkey-in-Europe), Turkmenistan, Ukraine, Uzbekistan and in part of United Kingdom.
The black-tailed skimmer is abundant throughout its range and is one of the most commonly seen dragonflies in Europe. It holds a stable population and has no known major threats.
This species has expanded its range, assisted by the creation of gravel pits which give it the extensive open unvegetated areas it prefers. It was first recorded in Great Britain in Essex in 1934. It is decreasing rapidly in the Maltese Islands.
This dragonfly is found at any open water with bare patches along the shore where the patrolling males frequently rest in the sun. It also inhabits near slow-flowing waters. It favors lakes, slow rivers, ponds and sometimes marshy area, without dense riparian vegetation. Females are less bold and not encountered as regularly. Adults prefer to perch on bare ground and rocks.
It is a fairly large dragonfly (the length of 47–53 mm, 29–35 mm abdomen, rear wing 35–41 mm.) with relatively broad, flattened abdomen, but not as broad as to chaser species. With age, adult males develop extensive blue pruinescence on their abdomen, offset by yellow lateral patches. The middle lobe of the pronotum is large and notched in the middle. The chest is yellow or yellowish-brown. The base of the hind wings do not show a dark opaque spots. The pterostigma is dark brown or black. On the front wings pterostigma 2–3 mm long. Anal appendages are black. The females and immature males are a deep yellow color, with wavy black lines dorsally on their abdomen. Males and females have the costal vein (the leading edge of the wing) yellow or black.
The species is similar to its much more localized congener the Orthetrum albistylum, but readily identifiable in the field. The males develop a blue pruinescence on the abdomen darkening to the rear with S8-10 becoming black. Its eyes are very dark green. They fly swift and low, skimming the water surface. Females retain their color and markings though they become quite grayish brown with age. This species could be confused with Keeled skimmer or Scarce chaser.
