Scarce Chaser

A species of lowland river floodplains that usually inhabits slow-flowing, meandering rivers and large dykes. Occasionally occurs in 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. Ovipositing females require areas of slow flowing open water, and the adults require some shrub or tree shelter.

• Inappropriate river management.
• Inappropriate river improvement schemes.
• Pollution.
• Eutrophication.
• Over-shading.
• Changing water levels.
• Excessive boat traffic.

Scarce in Britain and is consequently listed under category 3 (scarce) in the British Red Data Book on Insects.
The 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.

The male could be confused with Black-tailed Skimmer or Keeled Skimmer. The blue eyes help to distinguish it.

General management principles include maintaining inhabited sites and the adjacent landscape, controlling water quality, controlling boating activity, and undertaking monitoring and research. There are also best practice guidelines for managing inhabited sites, particularly regarding dredging, management of aquatic vegetation, and scrub control.

• Length: 40-49mm
• Dark wing bases and often black wing tips.
• Male: blue eyes. Blue body with  black tip to the abdomen.
• Female: brown eyes. Ochre coloration with black markings down the middle of the abdomen.

Skimmers and Chasers have a squat, spider-like body-shape, a square back to the head and small eyes.

22-25mm

Eyes point out to the side of the head.

Labial palps have weak serrations.

Dorsal spines long and curved.