Species Focus - Small Bluetail (Ischnura pumilio)

One of the rarer Damselflies to look out for in North Wales is the Small Bluetail or Scarce Blue-tailed Damselfly (Ischnura pumilio). The difficulty of course is finding one, particularly given their similarity to the Common Bluetail or Blue-tailed Damselfly (Ischnura elegans), which is indeed very common.

However, you can greatly improve your chances of finding the Small Bluetail by understanding and focusing your search on its more specialised habitat. The Common Bluetail can be found at many lowland ponds, however the Small Bluetail is much more selective.

You need to concentrate your search on open, shallow, poorly vegetated, seepage/flush streams. They prefer early-stage successional habitats such as abandoned quarries or fen flushes where livestock trample the margins and keep it open. They also like a silty substrate for their aquatic larvae to hide in.

The Small Bluetail is spreading north and east in the UK perhaps benefiting from a warming climate. We’ve certainly had several new sites for this species in the Cofnod area in recent years.

To separate Small Bluetail males from the Common Bluetail, you’ll need to consider the extent and position of the blue markings on the tip of the tail. An excellent comparison can be found here.

Abdominal segment 8 (counting from the front backwards) is black & blue in the Small Bluetail male, but entirely blue in the common Bluetail. In contract segment 9 is predominantly blue in the Small Bluetail, but black & blue in the Common Bluetail. This arrangement gives the impression that the ‘blue tail marking’ is further down the abdomen in the Small Bluetail.

Young females of the Small Bluetail are an attractive orange colour too, but you’ll need to consult more specialist literature to separate mature females of both species. High quality photographs are well-worth taking to help with your identifications.

If you see Small Bluetail in North Wales please submit your records, preferably with photographs, to the Cofnod ORS or the LERC Wales App.

Further resources: