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Sympetrum sanguineum (Miller) Ruddy darter
Description S. sanguiheum is one of the small libellulids in which the abdomen of males is
predominantly red. This coloration is blood-red, and is more uniform and brighter
than male S. stholatum. There are two prominent black marks mid-dorsally on
abdominal segments 8 and 9 and they may cause confusion with S. striolatum which
possesses similar though less prominent markings. However, unlike S. stholatum, the
abdomen is noticeably constricted at segments 3-5, giving it a clubbed appearance
(similar to the black-bodied S. danae), and the pterostigmata of mature individuals are
red, not brown. In immature males, and in females, the abdomen is predominantly
yellow-brown with black markings. The dorsal surface of the thorax lacks the large
blacktriangular mark that is characteristic of S. danae. The sides of the thorax are
extensively marked with yellow and black, much brighter than in mature males. The
hind wings of both sexes have a small but distinct saffron suffusion at their base. The
legs are black.
Habitat S. sanguineurn breeds in the marshy margins of ponds, lakes (including old clay pits
and gravel pits), canals and ditches, where there is an abundance of tall emergent
plants such as horsetails, reed sweet-grass and bulrush. In coastal ditches, sea
club-rush is often prevalent. It can breed in quite brackish conditions.
Breeding biology It is uncertain whether S. sanguiheurn is territorial. Its highest steady density is about
16 males per 100 m of water's edge. Males maintain a small exclusion zone around
themselves and chase off intruding males (Convey 1989). They have a rather 'skippy'
flight, quite unlike S. stholatum. Oviposition takes place in tandem or alone. When in
tandem, the pair adopt an undulating movement in flight during which the female's
abdomen is swung downwards and the eggs released, sometimes singly, low down
amongst shaded vegetation, less commonly over open water. S. sanguine= will
oviposit in habitats which have temporarily dried up. The species can have both
diapause and non-diapause eggs. The weed-dwelling larvae usually complete
development in one year.
Flight periods S. sanguineum is on the wing from late June to mid-September. It may be seen with
other species that favour marshy fens and ditches, notably Coenaghon pulchellum,
Lestes sponsa and Libellula quadhmaculata. It can occur with S. stholaturn, a species
seen more commonly over open water than S. sanguineum, which prefers the
vegetated margins. Populations are probably augmented in most years by
immigrants from the continent.
Status and distribution
European and
world distribution
In Britain, S. sanguine= has a south-easterly distribution. It is rare in the south-west
and Wales, and is scarce in the north midlands, though there has been an increase in
records recently It breeds as far north as Barnsley, Yorkshire. Reports of a population
crash in the 1970s were erroneous, and may have resulted from a misreading of an
earlier BRC distribution map, which showed many more pre-1960 than post-1960
records. Many of these earlier records were the result of periodic large influxes of
immigrants in the 1930s and 1940s, and did not necessarily represent breeding
populations. Longlield (1949b) stated that S. sanguiheum was probably increasing as
a breeding species in Britain. This increase appears to have accelerated in the past
decade or so, and has been noted in Essex (Benton 1988), Bedfordshire (Dawson
1988) and Gloucestershire (Holland 1983). However, S. sanguine= has disappeared
from a number of localities, being very susceptible to permanent changes in water
level due to improved drainage, and to natural seral changes in habitat. In Ireland, S.
sanguine= has increased during this century King and Halbert (1910) did not record
it as Irish. Longfield (Corbet et al. 1960) referred to having given to Lucas one of the
first pairs of S. sanguine= to be found in Ireland, taken in 1928. It is now fairly widely
distributed; it is most commonly found in the fens and marl lakes of the midlands, and
occurs frequently on turloughs.
S. sanguine= occurs throughout most of Europe, except northern Scandinavia and
some Mediterranean islands, and east to western Siberia. It is also found in North
Africa.
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