Article by Abigail Pedlow
This is one of those few cases where the species called ‘Common’ is actually common. In fact, Common Darter is the commonest Odonata species on our database, with Ruddy Darter almost a tenth as rare.
These two species are amongst the smallest dragonflies (as opposed to damselflies) in the UK, at around 3.5-4.0 cm long with a wingspan of around 5.5-6.0 cm. Ruddy Darters are slightly smaller than Common Darters.
Both species can be found basking on bare ground and rocks, and perching on twigs and branches.
They both fly from June (Common emerging slightly earlier than Ruddy) right through to September. In a mild year Common Darter can last even through to October/November. My latest sighting of Common Darter, across the river on the Gwent Levels, was in November.
The females of both species are yellow-brown with black markings, and the males of both species develop a red colouration as they mature, with black markings on the end of the abdomen.
Habitat
Common Darters are widely distributed and can be seen around garden ponds, canals, lakes, ditches and rhines and slow-moving rivers.Ruddy Darter is restricted to breeding in the well-vegetated margins of waterbodies, where there are lots of tall emergent plants – as a result they are vulnerable to over-enthusiastic vegetation clearance. They can tolerate brackish water.
Appearance
It’s all in the legs! (close-focusing binoculars very useful here). Common Darters (both male and female) have dark legs with a yellow stripe on the outer surface. Ruddy Darters (both male and female) have black legs.
The abdomen of the male Common Darter is generally a paler, slightly orangy, red than the blood-red of Ruddy Darter.
Ruddy Darter males have a noticeable constriction on the abdomen – a ‘waist’ which gives them a clubbed appearance.
Common Darter males have pale markings on the thorax, Ruddy Darter males don’t – giving them an overall darker appearance. Ruddy Darter males also have a red face.
According to the books Ruddy Darter has a more ‘skippy’ and ‘bouncy’ flight than Common Darters. This isn’t something I’ve noticed so I shall be looking out for it this summer!