Most odonata exhibit sexual dimorphism, i.e. the males and females don’t look alike, but in the case of the Large Red Damselfly (Pyrrhosoma nymphula) the main coloration is the same and the differences are more minor. So, telling the sexes apart is a little trickier than normal.
This species is complicated by there being four female colour variations, further confused by varying terminologies:
- typica or intermedia: normal or middle amount of black on the red abdomen
- fulvipes: reduced black on the red abdomen
- abdomen all black dorsally with some red
- abdomen all black dorsally with no red
Notice that the antehumeral stripes for males and females begin adult life as yellow, both maturing to red. This is sometimes missed for females.
I have no personal records of either form of melanotum, but here is my attempt to clarify the gender and maturity differences together with the female fulvipes and typica forms.
As usual, clicking on the diagram will get you a larger, more readable image.