reaches of the Stour on the northern boundary of Essex (TL74 and TL84) the upper
reaches of the Chelmer (in TL61 and TL62) and of the Roding (TL51 and TL52) add
Enallagma cyathigerum and Calopteryx splendens to this puny list, whilst other common
species such as Aeshna mixta and Sympetrum striolatum have been observed (not,
however, as definite breeding species).
The middle and lower reaches of these major Essex river-systems are much more
suitable as dragonfly habitats. Along the Lee and Stort in the west, and the Chelmer/
Blackwater Navigation in mid-Essex, there remain extensive water-meadows with
associated unpolluted ditches, and relict areas of fresh-water marsh. In some of these
rivers (notably the Stort/Lee complex and the Chelmer/Blackwater) canalisation
implies a slow, regulated flow of water, and there are also extensive stands of rich and
diverse aquatic, emergent and marginal vegetation. Ditches, backwaters, and
alterations in depth, flow and substrate along the length of these rivers adds further to
habitat diversity, and so makes for a rich dragonfly fauna.
Floating-leaved aquatic plants such as Water-lilies, Broad-leaved Pondweed and
Arrowhead thrive in the best of these slow-moving rivers and their tributaries, and
where they do occur they are used as perches, for egg-laying, and as 'basking' sites by
such species as Enallagma cyathigerum and, more rarely, Erythromma najas. When
allowed to develop, emergent vegetation includes such species as the Bulrush, Reed-
mace, Sweet Flag, Branched Bur-reed and Flowering Rush, whilst such species as Reed
Sweetgrass, Meadowsweet, Water Figwort, Celery-leaved Buttercup, Water Dock,
Purple Loosestrife and Water Forget-me-not flourish on the bank-sides and in the
associated marshes and ditches.
Sites with a diverse assemblage of such plants as these, especially if relatively
sheltered by trees or hedgerows tend to have the richest dragonfly fauna. Of our twenty-
two breeding species of Odonata, fifteen have been observed to breed in slow-moving
rivers and canals in the county, and it is possible that this underestimates the true figure.
Many of these species (such as those already mentioned as inhabiting the inhospitable
upper reaches) are common in other, still-water habitats, but others are quite
characteristic of moving water. These include Calopteryx splendens which, although it
occurs in the swifter upper reaches, is at its most abundant downstream. This
spectacular damselfly is common along suitable stretches of most of our main rivers
and their tributaries. The equally spectacular Anax imperator is a notable breeding
species of rivers as well as still-water sites, as is Aeshna mixta. Two local damselflies,
Lestes sponsa and Pyrrhosoma nymphula both have breeding sites on these reaches of
some of our rivers, and in associated ditches and marshes, though such habitats are
somewhat atypical for them (especially in the case of Lestes sponsa).
Finally, two of our most local damselfly species also occur on slow-moving reaches of
certain of our river-systems. Platycnemis pennipes (the White-legged Damselfly) favours
richly vegetated sites with unpolluted water. It is declining nationally and appears also
to have been lost from some of its former Essex sites (most notably the Stour). Its
remaining strongholds are the Lee Valley and Roding, in the west, together with the
Chelmer/Blackwater complex in mid-Essex. A second nationally very local and
declining species is Coenagrion pulchellum, which has been observed in Essex only once
during the survey period, on the Old River Lee.