extreme north-west of the county. Apart from the north-west, breeding sites have been
located across the county, and they include rivers, lakes, ponds, gravel-pits and coastal
dykes. Understandably, confirmed breeding records are only a small proportion of total
records for the species, so it is difficult at this stage to ascertain how much of the
abundance of this species is due to local breeding success, and how much to a
succession of good years for immigration. My own (admittedly rather subjective)
impression is that A. mixta is now widespread and increasingly successful as a breeding
species throughout most of Essex. The apparent absence of the species from the north-
west is worth further investigation.
Anax imperator (Leach, 1815) Emperor Dragonfly
This is probably the only species of dragonfly whose English name is already in
widespread popular usage. The Emperor is one of our largest and most spectacular
hawker dragonflies, readily identified by the pattern of bright blue (in the male) or green
(in the female) with a black median line along the length of the abdomen.
Anax imperator is seen less often than the other hawkers away from water. The males
are fiercely territorial, and can be observed hawking tirelessly over a regular beat along
the edge of a pond or stream. This patrolling is occasionally broken by brief, swift sorties
out over open water, or over dry-land, or by skirmishes with other dragonflies within, or
at the edges of the defined territory. Hostile action will be elicited by other males of the
same species, other hawkers (I observed one 'buzz' an ovipositing female of Aeshna
cyanea), as well as smaller darters such as Orthetrum cancellatum. This territorial activity
limits the numbers of this species found at any one site in relation to the extent of the
water-fringes. D. S. Walker (pers, comm.) observed a successive reduction in the
numbers of males present at one site as Greater Reed-mace progressively reduced the
area of open water, and hence the circumference of the pond.
Anax imperator will take larger insect-prey than is typical of other hawkers. I have
observed large butterflies such as Meadow Browns and Small Tortoiseshells taken on
the wing, as well as beetles (such as Ladybirds). Smaller prey are usually consumed as
the dragonfly continues its patrol (inedible parts such as wings fluttering down), but
sometimes it has to briefly alight on marginal vegetation to deal with the larger prey. On
one occasion I observed a male A. imperator eventually release a badly damaged Small
Tortoiseshell after struggling for some seconds to consume it in flight.
The females oviposit 'solo', usually settling on floating-leaved vegetation, or on
aquatic plants just below the surface. The abdomen is curved round, and the eggs are
laid on submerged water-plants. Chosen sites for oviposition observed in Essex recently
include flooded gravel pits, farm reservoirs, ornamental ponds and lakes, and three
moving-water sites (the Cornmill Stream, River Roding and Sandon Brook). It is
sometimes on the wing as early as the end of May and as late as the last week in August,
but it is at its most common in July.
The Emperor appeared (under the name A. formosa) on E. Doubleday's (1835) list for
his locality to the east of Epping and J. F. Stephens (1835-7) also gave Epping as a
locality for it. H. Doubleday (1871) described it as 'very common formerly' on
Coopersale Common, and also as occurring at two large ponds by the 'new road'
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