The damselflies are usually slender with forewings and hind wings of equal length. The head is also wider than the thorax and the eyes are usually on the opposite sides of the head. Most also fold their wings along their body when at rest. There are about 20 species found in the UK.
The number of species in each family, taken from CoL, is just to give a general idea and is not necessarily up to date. I have only listed the species where I have a photograph.
Superfamily Hemiphlebioidea
Family Hemiphlebiidae – ancient greenling — 1sp.
Superfamily Coenagrionoidea
Family Coenagrionidae – pond damselflies — 1,143 sp.
Enallagma cyathigerum, Common blue damselfly
Pyrrhosoma nymphula, Large red damselfly
Family Isostictidae – narrow-wings — 46 sp.
Family Platycnemididae – white-legged damselflies — 220 sp.
Family Platystictidae – shadow damsels — 224 sp.
Family Protoneuridae – thread tails — 273 sp.
Family Pseudostigmatidae – forest giants — 18 sp.
Megaloprepus caerulatus, Helicopter damselfly
Superfamily Lestoidea
Family Lestidae – spread wings — 150 sp.
Lestes sponsa, Emerald damselfly
Family Lestoideidae – blue streaks — 13 sp.
Family Megapodagrionidae – flat wings — 310 sp.
Family Perilestidae – shortwings — 19 sp.
Family Pseudolestidae — 1 sp.
Family Synlestidae – sylphs — 38 sp.
Superfamily Calopterygoidea
Family Amphyipterygidae – relicts
Family Calopterygidae – demoiselles (or broad-winged) — 186 sp.
Calopteryx virgo, Beautiful Demoiselle
Calopteryx splendens, Banded Demoiselle
Family Chlorocyphidae – jewels — 147 sp.
Family Dicteriastidae – barelegs
Family Euphaeidae – odalisques — 70 sp.
Family Polythoridae – bannerwings — 57 sp.
Most of these were taken in the UK.
Family Coenagrionidae — pond damselflies ~ 1,143 sp.
Enallagma cyathigerum
Common blue damselfly mating on Thursley Common – July 2017
Enallagma cyathigerum
Common blue damselfly (male) at RSH Wisley Gardens – July 2017
Pyrrhosoma nymphula
Large red damselfly (male) – in the garden in Elstead – July 2017
Pyrrhosoma nymphula
Large red damselfly (female) – at Ebernoe Common – May 2017
Family Pseudostigmatidae — forest giants ~ 18 sp
Megaloprepus caerulatus
Helicopter damselfly at La Selva in Costa Rica – February 2015. This helicopter damselfly was raelly quite big! It’s the largest damselfly in the world with a wingspan of up to 19 cm.
Family Lestidae — spread wings ~ 150 sp.
The gallery was not found!
Family Calopterygidae — demoiselles ~ 186 sp.
Calopteryx virgo
Beautiful Demoiselle (female) – along the river Wey at Godalming – July 2017
Calopteryx virgo
Beautiful Demoiselle (male) – along the river Wey at Farncombe – June 2017
Calopteryx virgo
Beautiful Demoiselle (female) – along the river Wey at Farncombe – June 2017
Calopteryx splendens
Banded Demoiselle (male) – along the river Wey at Farncombe – June 2017