Common vs Ruddy Darters

Common vs Ruddy female

If you can get good views of the legs or face then there should be no problem working out if an insect is a female (or immature male) Ruddy or Common Darter. Note in the frontal view of the composite picture below that the Ruddy female appears to have 'shoulder stripes' and the Common female almost has a 'Dark T'. These are 'indicative' features when comparing the two species - the key features are the legs and the extent of black on the frons.

Common vs Ruddy male

When seen well mature males of these two species should not be confused - the image is annotated with the salient features. It's also worth remembering that with old male Common Darters the thorax becomes very dark and the markings obscured.

You will read in field guides (and on the preceding web page!) that Common is an orange red and Ruddy is blood red. Colour varies a lot with age (and with the lighting conditions and through colour perception of the observer). Ruddy has a more clubbed abdomen than Common but 'clubbedness' develops with age and the feature is only really useful if you can view the dragonfly from above - it can be very difficult to see from the side or head on. Some Common Darters can appear to have a clubbed abdomen.

For example, I can't see much difference in the colouration of the males in the image below and the Common darter has a (slightly) clubbed abdomen. I always try to get at least one additional feature for ID - in this composite photo the legs are showing well so you can use that for ID.