Scarce Chaser - Libellula fulva
Adult sizeOverall length: 42 - 45mm Hindwing length: 32 - 38mm
Distinguishing featuresFor once the females and immature males of this species are the most identifiable being bright orange-brown with a black central line on the abdomen and uniquely patterned. Males are more difficult to separate from other species being superficially similar to the two skimmers. Locally common on many Dorset rivers but rare nationally, listed as category 3 (scarce) in the British Red Data Book on insects.
Identification - for help with terms see glossary
The mature male Scarce Chaser possesses pale blue pruinescence on the abdomen and the last 3 segments are black. Often in older males they take on a rather dirty appearance as the blue is scuffed up. The eyes are blue, thorax black with no stripes. Has dark wing patches at the base of the hind wings.
Very similar colour to mature females perhaps with an even more vivid orange colour to the abdomen, eyes and thorax. Abdomen has black bell like markings forming a distinctive line. Wings are suffused with yellow-orange along front of both wings
Eyes are brown, thorax is olive-brown and abdomen is orange-brown with bell shape black markings, very similar to immature male. Wings have dark wing bases and yellow suffusion across front edges of both wings. In older females the abdomen turns a dull brown colour.
Paler version of mature female
HabitatThe Scarce Chaser is a species of Lowland river floodplains and usually inhabits slow-flowing, meandering rivers and large dykes. Occasionally mature gravel pits and nearby ponds also support populations. Inhabited sites characteristically have good water quality, which supports submerged and floating plants as well as prolific stands of emergent vegetation.
BehaviourMales will tend to spend much time perching on dense vegetation overhanging rivers and will actively defend territories as with the other chasers and darters. Females and immature males can be found close to water in bankside vegetation and also away from water while they mature.
Status and distributionThe Scarce Chaser is restricted to 6 main localities in Norfolk/Suffolk, Sussex, Wiltshire/Somerset, Cambridgeshire, Kent and Dorset/Hampshire. Populations appear to be stable and there is evidence that suggests that it may be expanding its range. Can be locally common along some slow moving clean rivers such as the Stour in Dorset.
Flight periodMain flight period is April to July peaking in June.
Click on the photos below to enlarge...
All photographs by kind permission & © of Ken Dolbear unless otherwise stated. All rights reserved.