6
RED-VEINED DARTERS SEEN IN ESSEX
On July 31st 1994 Bill Varney visitedthe area around St Peter's Chapel, Bradwell-on-Sea
to photograph dragonflies. On arrival he noticed at least six Migrant Hawkers Aeshna
mixta, a couple of Ruddy Darters Sympetrum sanguineum and what, at first, he took to be
a dozen or more Common Darters S. striolatum frequenting an area of rough grassland
along the sheltered side of a small thicket, adjacent to the seawall. On closer inspection,
however, he noticed that some of the last named, which were all females or immature
males, seemed larger and brighter yellow in colour than their companions and had a
distinct reddish sheen to their wings. Suspecting that they might be Red-veined Darters
S. fonscolombii he informed the four people (including myself) who were staying at the
nearby Bird Observatory and during the next few hours we were able to confirm that that
indeed was what they were.
The chief distinguishing characteristics appeared to be 1). Size: they were noticeably
longer bodied and had a broader wingspan than the Common Darters, a difference that
soon became easy to pick out even when direct comparison between the two species was
not possible. 2). The face, thorax and abdomen all seemed to be brighter yellow than on
the Common Darters whilst the sternites were black, giving a dark edge to the sides of the
abdomen. 3). The eyes were yellow or reddish-yellow above, blue-grey below. 4). The
costa and sub-costa were red along their entire length - an obvious feature; so too the
smaller veins in the wing, although these were more easily observed when viewed against
the light. At such times the wings had an almost crimson sheen whilst when the light was
from behind they sometimes showed a more yellowish tint and in shadow appeared
blueish or merely dark. 5). The pterostigma on all individuals was either colourless or
pale yellow, heavily outlined in black. 6). The anal appendages on at least one of the
immature males was noticeably longer than on those of the Common Darters, appearing
like a pair of claspers.
They were observed for a period of around four hours, most of which time they spent
either hunting or sunbathing. On one occasion a young male made a brief attempt to mate
with a female; the latter curving her abdomen towards the male invitingly when he
approached but he soon lost interest and moved off. It was also noted that the Red-veined
Darters seemed to perch on taller pieces of vegetation than the Commons. They were
present until at least the early afternoon but neither they nor the Migrant Hawkers could
be refound after 3pm.
On the previous day the weather had been hot and sultry with a strong south-easterly
wind, culminating in overnight thunderstorms arriving from the Continent. Neither the
Migrant Hawkers or Red-veined Darters had been present on the 30th, the implication
being that they arrived ahead of the stormy weather. Their appearance coincided with the
arrival of several migratory moths, notably, the Ni Moth Trichoplusia ni, Bordered Straw
Heliothis peltigera and several Humming Bird Hawk Moths Macroglossum stellatarum.
This record has been accepted by the British Dragonfly Society and appears to be the first
sighting in Essex of this migrant species, which is a regular visitor to the southern
counties of England.
Graham Smith