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Status and distribution
Libellula quadrimaculata Linnaeus Four-spotted chaser
Description This libellulid is predominantly brown in both sexes, but with striking wing
coloration when observed closely. It takes its name from the dark mark at the
node of each wing. There is also a black patch at the base of the hindwings,
crossed by yellow veins, and a deep saffron suffusion on the basal area of each
wing which extends towards the node. The thorax is brownish and covered in
dense pale hairs. The abdomen, which tapers posteriorly is brownish except
for the posterior third, comprising segments 7-10 and part of 6, which is black
dorsally Also, there are narrow yellow marldngs laterally on segments 4-8,
sometimes also 9. A variety known as f. praenubila Newman occurs not
uncommonly. It is characterised by a dark patch towards the end of each wing
near the pterostigina.
Habitat L. quadrimaculata breeds in a wide range of mainly still water habitats: from
the dykes of coastal levels to bog pools and lochans in mountain areas. It is
also found in ponds, lakes and canals.
Breeding biology The males are very territorial. They make their sallies from sticks and tall
emergent plants on which they perch, and also patrol the water's edge. Their
highest steady density is about 15 males per 100 m of water margin but, when
exceptional numbers are present in the vicinity of a pond, the territorial
system breaks down for a period. Warren (1964) observed territorial
behaviour in L. quadrimaculata at a bog pool that was occupied also by
Leucorrhinia dubia. He noticed that the two species hunted over the same area
but at different levels. Provided the L. dubia remained low, it would not be
molested, but if it flew up to the level at which the L. quadrimaculata was
perched, about 70 cm from the ground, it would be attacked, and the L. dubia
individual would be chased away over the trees, only to return a few minutes
later. Copulation takes place in flight, and lasts only 5-20 seconds. The
female hovers, often where there is vegetation not far below the water surface,
and drops her eggs into the water by flicking her abdomen downwards. The
eggs sink and adhere to the vegetation. The male usually keeps guard nearby
and wards off intruders. However, females also oviposit alone. The larvae live
amongst the bottom debris, and probably take two years to develop.
Emergence often occurs on marginal rushes such as soft rush.
Flight periods L. quachlMaculata is on the wing from late May to early August, and can be
seen with the many other species that favour static water sites.
It is widespread throughout Britain and Ireland, including the Orkneys and the
Outer Hebrides, but is absent from many apparently suitable sites in the
Pennines and north-east England.
European and world L. quadrimaculata is an holarctic species that occurs throughout most of
distribution Europe, though local in the extreme north and south. Its range extends east to
Japan, and to North America. On the continent, vast migrations are known to
occur, which tend to have a cycle of ten years or so. Mass migrations rarely
take place in Britain or Ireland, although they have been recorded from Essex
and Kent in the past. Immigration in small numbers may occur more
frequently however.
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