Black-tailed skimmer  (Nesciothemis farinosa)

The black-tailed skimmer is classified as Least Concern (LC) on the IUCN Red List (1).

The black-tailed skimmer (Nesciothemis farinosa) is a fairly large and robust dragonfly (2). The male, as the common name suggests, has a distinctly black tail. Its head is also black, while the eyes are brown-black above and lighter below. The thorax is powdery blue-grey, while the abdomen is blue-grey for the first five segments, but becomes black with pale yellow markings on the upper side of the remaining segments. These markings become darker, sometimes almost black, as the dragonfly ages. The abdomen of this species is straight and pointed. The wings of the male black-tailed skimmer are mostly clear, becoming opaque and smoky-grey as the individual becomes older (2).

The female black-tailed skimmer is very different to the male in appearance, with a wholly light brown face, a brown labrum that is margined with yellow, and a brown thorax, which is lighter on the sides and darker above. There is a distinct pale brown or cream line, separating the upper and lower sides of the thorax, and the abdomen is yellow-brown with a darker line running along the length of both sides. The young female black-tailed skimmer has clear wings with brown tips, which disappear and begin to turn smoky-grey as the individual ages The pterostigma, a thickened cell found on the outer edge of the wing, is deep yellow-brown in the male and female (2). 

The most widespread species in the genus Nesciothemis (3), the black-tailed skimmer is found in most countries of sub-Saharan Africa, from Egypt in the north, south throughout Africa to South Africa, and from Angola in the west to Somalia in the east (1).

The black-tailed skimmer can be found up to elevations of 1,200 metres in South Africa (2), and between 800 and 1,890 metres in Malawi (4). 

The black-tailed skimmer is found in forest, bush, savanna and woodland (1). Within these areas, its preferred habitat includes freshwater pools, pans, marshes and quiet reaches of rivers where it can perch on reeds or tall grass (2) (4).

The larvae of the black-tailed skimmer can be found in springs and other small water bodies with dense reed vegetation (3).

The flight period of the black-tailed skimmer is between October and May in the South African part of its range (2), and between March and June in Namibia. Peak population numbers occur around mid-January (5).

Little is known about the biology of the black-tailed skimmer. However, like most other dragonflies, it is likely to be an opportunistic predator, detecting its mainly insect-based prey by sight (6).

As in other dragonflies, breeding begins with the male grasping the female by the head using a pair of claspers on the tip of the abdomen. If the mating is successful, the female lays a clutch of eggs immediately. In some species, the male may guard the female while the eggs are laid, to prevent other males from mating with her (6).

The black-tailed skimmer, like all dragonflies, begins life as an aquatic larva. The larva goes through many stages of development before a final moult occurs, at which time the larva leaves the water and metamorphoses into an adult. After this, there is a maturation period during which the adult colouration develops and the wings harden, enabling the adult dragonfly to fly (6). Larval development is thought to take about eight months in this species (3). 

There are currently no known threats to the black-tailed skimmer (1). It is likely that this species, as with other dragonflies is threatened in certain parts of its range by the destruction and degradation of the wetlands it inhabits (6) (7). 

Building artificial ponds with a range of habitat conditions has been tested in South Africa to improve the diversity of dragonflies in the area, including the black-tailed skimmer (8). However, no conservation measures are currently known to be in place for this species (1), and more research is needed to implement appropriate conservation measures. 

Find out more about invertebrates and their conservation:

• Moore, N.W. (1997) Dragonflies: Status Survey and Conservation Action Plan. IUCN/SSC Odonata Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at: 
  http://data.iucn.org/dbtw-wpd/edocs/1997-042.pdf