Flight period: May to August (less abundantly also in late April, September and October)
Females and immatures: pale, yellowish brown with tho bold lines running along the length of the abdomen. The wings have a yellow costa and a very dark brown or black pterostigma.
Male: develops a blue pruinescence on the abdomen darkening to the rear with with S8-10 becoming black. Its eyes are very dark green. They fly swift and low, skimming the water surface.
Females retain their colur and markings though they become quite greyish brown with age.
Dr. Chris Thomas photographed and timed the hatching sequence of a female Black-tailed Skimmer and has placed it on the web as part of a longer photo tour of the BBC Springwatch East Day at Marston Vale, June 2006. The first photo of the sequence can be found here.