Darters - Common or Ruddy?

There are two species of Darters that at first glance may look very similar and can be easily confused for one another so I thought I would share some very recent images.

The Common Darter (Sympetrum striolatum) is the larger of the two with an abdomen length of 25-30mm. Both species will perch with the wings held forwards.

Immatures and female Common darters have a yellowish to light brown abdomen. Mature females take on a much darker hue. On both males and females the divisions between the abdominal segments are much more prominent than on the Ruddy.

Both the male and female Common have two distinct yellow patches on the side of the thorax and this is a clear feature to assist immediate identification. Both the males and females have a similar tiny basal yellow spot on the wings (similar to the Ruddy).

The abdomen of the mature Common males is orange-red and therefore much lighter than the blood-red colouration on the Ruddy. Often very difficult to see are the yellow stripes on the legs.  

When viewing side on you should note that there is no black line extending down the length of the abdomen.

The Ruddy Darter (Sympetrum sanguineum) is smaller than the Common (abdomen length: 20-26mm) and the mature male has a distinctly waisted blood-red abdomen and much darker sides to its thorax (see below) and the black line over the fronds extends fully down the sides. The legs are totally black whereas the legs on the Common are striped with yellow but extreemly difficult to pick out with your eyes. It also has a similar tiny yellow spot at the base of the wing.

So next time you are out and about keep a watchful eye open for these two species which often share similar habitats. They will be around for a while yet (even into late October) and hopefully you will now know which is which.    FAB.