— Posterior margin of prothorax deeply
indented. Blue thoracic stripes variable,
but usually incomplete.
'U'-shaped mark on segment 2 of the
abdomen with a 'stem' linking it to hind
margin of the segment.
Variable black marking covering most of
segment 9.
Anal appendages as shown (Extremely
rare in Essex) Coenagrion pulchellum
male
(Variable Damselfly)
20 Abdomen mainly black, with one clear
blue segment (8). Sides and part of dorsal
surface of thorax pink.
(Transitional colour form.) Ischnura elegans.
form rufescens of
the female
(Blue-tailed Damselfly)
— Not as above ...................................... 21
21 Abdomen black or dark brown (no blue
segments, or significant areas of blue on
abdomen) ...................................... 22
— Abdomen green or blue with black
markings ...................................... 23
22 Thorax and abdomen almost completely
black (viewed dorsally). Thoracic stripes
short. Eyes dull red. Erythromma najas
female
(Red-eyed Damselfly)
— Abdomen almost completely black (dark
brown on segment 8). Thoracic stripes
complete (form infuscans) or if absent.
replaced by brown on thorax (form
infuseans-obsoleta). Eyes not red. Ischnura elegans
female (colour-forms)
— (Dark examples of C. puella female may 
(Blue-tailed Damselfly)
key out here - note thistle mark on
segment 2.)
23 No long black marks on side of thorax."
Black markings on segments 3-8 usually
forward-pointing arrow-shaped. Small
projecting spine on ventral surface at
hind end of segment 8 (detect by touch, or
by viewing with lens from side.)
121