Bedfordshire Odonata - Scarce Chaser

Scarce Chaser – Libellula fulva

European common name: Blue Chaser

BDS pronunciation: lib-ell-yew-lah full-va

The Scarce Chaser – Libellula fulva, is a mid-sized dragonfly that undergoes striking colour changes during its life.

Classification:

Odonata
	Anisoptera		Dragonflies
		Libellulidae	Chasers, Skimmers, & Darters

A mid-sized dragonfly that is has become much more common in recent years and can be abundant at some locations. Its mass emergence is spectacular, and the immature male and female’s appearance is far more striking than the adult.

As immature dragonflies the male and female are similar in appearance and are very distinctive, with a bright orange body with a prominent dark dorsal stripe along the medial line of the abdomen. Eyes are chestnut brown. The wings feature vivid orange venation from the base to the node, dark basal wing patches, and dark pterostigma.

Both sexes lose their vivid colouring and orange venation as they mature.

Males develop a pale blue pruinescence on their abdomen as they mature, covering the dorsal surface except for the tip, which remains black. The eyes become grey or pale blue in colour.

The female darkens with age, eventually turning brown, the eyes also darken and become greyer. Females usually have more prominent dark spots at the wing tips than the male, where it is either absent or only vaguely present.

Overall length: 42 – 45 mm
Wings: 32 – 38 mm

Immature Scarce Chasers are unlikely to be mistaken for any other species, but mature adults may be confused with several other Skimmer and Chasers.

Broad-bodied Chaser – Libellula depressa
The Broad-bodied Chaser has a more obviously broad body and features prominent basal wing patches on all four wings, and dark brown eyes. The male has a much less noticeable black tip to the abdomen, and the female is more yellow overall, with bright yellow abdominal markings.
Four-spotted Chaser – Libellula quadrimaculata
Only the Four-spotted Chaser females are similar but are easily told apart by their diagnostic wing patterns, yellow abdominal spots and dark eyes.
Black-tailed Skimmer – Orthetrum cancellatum
Only males are similar, but the wings lack basal patches and have yellow costa. The thorax is lighter in colour and overall the Black-tailed Skimmer has a brighter appearance and is longer and more narrow.
Keeled Skimmer – Orthetrum coerulescens
The male is a possible confusion species owing to its pruinosed abdomen, but the Keeled Skimmer lacks a black tip to the abdomen, and is much more slender in appearance and more Darter-like than the Scarce Chaser. Its wings have yellow costa and lack basal wing patches.

Favours slow rivers, but also found at still water sites. Surrounding water meadows and areas of dense vegetation are important as hunting grounds, and tall vegetation is preferred for basking and guarding territory.

Previously restricted to a few sites in the north-east of the county at Wyboston, but now extending its range considerably. It is locally common along the River Great Ouse between Roxton and Kempston, and is now a much more common sight than it once was. There have been reported sightings at The Lodge in Sandy, home of the RSPB, and also at Felmersham NR.

Visible mid-May to late July, peaking in June.