Bedfordshire Odonata - Variable Damselfly

Variable Damselfly – Coenagrion pulchellum

European common name: Variable Bluet

BDS pronunciation: coin-ag-ree-on pull-kell-um

The Variable Damselfly – Coenagrion pulchellum, is a recent newcomer to the county. Its similarity with the more commonly encountered Azure Damselfly – Coenagrion puella, and its variable appearance, mean it’s easily overlooked.

Classification:

Odonata
	Zygoptera		Damselflies
		Coenagrionidae	Blue or red Damselflies

A rare but sometimes locally common damselfly, one of several similar species with blue and black markings. It is very similar in appearance to the Azure Damselfly – Coenagrion puella but has some distinctive features that help identification, however there is much variation between individuals.

The male has a predominantly blue body with black markings and features a characteristic ‘wine glass’ marking on the second segment – but note that this feature is very variable and the ‘stem’ may be absent. S9 is usually more extensively black than the Azure, resembling a ‘bat’. The male has narrow shoulder stripes on the side of the thorax that may be broken, giving the appearance of an exclamation mark ‘!’, helping separate this species from the most similar Azure, but this is not always the case and the stripes may not be broken at all.

The female has both dark (green) and blue forms. Black markings on S2 of the female are thistle shaped in the dark form, resembling a solid filled ‘Mercury’ symbol in the blue form.

Both the male and female show a pale bar between the eye spots, a feature not found on the Azure, but again this can be somewhat variable in appearance. The pronotum is more heavily lobed in both sexes than the Azure, but this is hard to see without magnification or a clear digital image.

Pterostigma are dark. Common to the Azure, Variable Damselflies sometimes rests with their wings held somewhat open, rather than closed.

Overall length: 33 – 38 mm
Wings: 16 – 23 mm

The most similar species is the Azure Damselfly – Coenagrion puella, and the differences are summarised below:

Feature	Variable Damselfly – Coenagrion pulchellum	Azure Damselfly – Coenagrion puella
Head	Pale bar between eyespots	No markings between eyespots
Pronotum	Heavily lobed, mostly black	Less obvious lobes, pale edge
Thoracic stripes	Often broken, resembling exclamation ‘!’ mark (this is very variable between individuals)	Usually continuous, unbroken stripe
Segment 2	Heavy ‘wine glass’ mark with ‘stem’ (this is very variable between individuals)	Black ‘U’ mark
Segement 9-10	Mostly black, ‘Bat’ shaped mark (with some variation between individuals)	Mostly blue, black, ‘bow tie’ mark

There are several other broadly similar species that might cause some confusion:

White-legged Damselfly – Platycnemis pennipes
Has paler colouring, white legs, and the black is less extensive on the dorsal surface of the abdomen. Has four shoulder stripes, rather than two.
Common Blue Damselfly – Enallagma cyathigerum
Has a ‘mushroom’ or ‘lollipop’ shaped marking on segment 2 of the male. Females are more difficult, but segment 2 more extensively black than in the Variable. Male and female have broader shoulder stripes on the thorax than the Variable and lack the ‘Coenagrion spur.’
Red-eyed Damselfly – Erythromma najas
Male: Is larger, with very obviously red eyes. Dorsal surface of the abdomen mostly black except for a prominent blue ‘tail-light’. All black thorax and no shoulder stripes from above.
Female: Is larger, with green or reddish green eyes. Dorsal surface of the abdomen more extensively black. All black thorax and incomplete shoulder stripes from above.
Small Red-eyed Damselfly – Erythromma viridulum
Male: Is smaller, with very obviously red eyes. Dorsal surface of the abdomen mostly black except for a prominent blue ‘tail-light’. Almost all black thorax but with a single narrow shoulder stripe from above.
Female: Is smaller, with green eyes. Dorsal surface of the abdomen more extensively black. All blue thorax with narrow green shoulder stripe from above.
Blue-tailed Damselfly – Ischnura elegans
Dorsal surface of the abdomen is mostly black, except for a prominent blue ‘tail-light’ (other colours in some female colour forms).

Favours ponds, lakes, ditches and slow rivers with plenty of vegetation.

Scarce but can be common at some sites. I’ve encountered them mainly at Felmersham NR and The Grange Estate, but they are probably under recorded due to their similarity to the Azure Damselfly – Coenagrion puella.

Visible from late April to August, peaking May to July.