Violet dropwing (Trithemis annulata)

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Violet dropwing fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Violet dropwing description

The violet dropwing (Trithemis annulata) is a distinctive dragonfly that is well known for its striking violet colouration, from which it gets its common name. The male of this species appears purple, but this is due to a bright red base colour on the abdomen and thorax, which is overlaid with a blue, powdery bloom (‘pruinescence’) on the surface, creating the vibrant violet colouration ⁽²⁾.

The violet dropwing is a small- to medium-sized dragonfly, and has a distinctly broad abdomen ^{(2) (4)}. Like many other dropwing species, the violet dropwing immediately lowers its wings on landing, a behaviour which gives this group of dragonflies their common name ⁽⁵⁾.

The male violet dropwing has a distinctive bright red face, red eyes, and red wing veins, and there is an amber patch at the base of each hindwing ^{(2) (3) (4)}. The abdomen has fine purple dashes along the top, with small black stripes on the top of the eighth and ninth abdomen segments ⁽⁴⁾.

In contrast, the female violet dropwing is not quite as vivid as the male. Instead, the female has a yellow-brown body, a large yellow patch at the base of the hindwing, and no red in the wing veins ^{(2) (4)}. The female violet dropwing can be distinguished from other female Trithemis species by its stouter abdomen and by the black marks on top of the eighth and ninth abdomen segments. Juvenile male violet dropwings first adopt a yellowish colour similar to the female, then later turn orange and red and finally the vibrant violet colour on reaching maturity ⁽²⁾.

Also known as

plum-coloured dropwing, violet-marked darter.

French

Trithémis Annelé.

Size

Total length: 3.2 - 3.8 cm ⁽²⁾

Abdomen length: 1.7 - 2.9 cm ⁽²⁾

Wingspan: 6 cm ⁽³⁾

Violet dropwing biology

Like other dragonflies, the violet dropwing begins its life as an egg laid in a water body by the female. After hatching, it spends the first stages of life as an aquatic larva, or nymph, which breathes through internal gills ^{(3) (6)}. The larva remains in the water as it passes through a number of developmental stages, undergoing a series of moults as it grows larger. Eventually, the larva emerges from the water and moults into the adult form ⁽⁶⁾. The adult violet dropwing then spends some time maturing until it is fully mature and capable of reproduction ^{(4) (6)}.

In most dragonfly species, the adult male perches near the waterside waiting for a female, and may defend a territory. During mating, the male holds the female by the head using specialised appendages, known as ‘claspers’, at the end of the abdomen. Male dragonflies have secondary reproductive organs towards the front of the abdomen, from which the female receives the sperm. While being held by the male, the female dragonfly bends the tip of her abdomen forwards to receive the sperm packet, creating a shape known as a mating ‘wheel’ ^{(3) (4) (6)}.

Many male dragonflies keep hold of or guard the female until the eggs are laid, to ensure no other males can mate with her ^{(3) (4) (6)}. As in other members of the Libellulidae family, the female violet dropwing is likely to scatter the eggs over the surface of the water by dipping her abdomen into the water while flying over it ^{(3) (4)}.

The violet dropwing larva is an opportunistic predator, catching prey by shooting out its enlarged and modified mouthparts ^{(3) (6)}, which are armed with hooks on the end ⁽⁶⁾. The adult violet dropwing is also an opportunistic and effective predator, using its acute vision to detect prey, and its outstretched, bristly legs as a ‘basket’ to capture insects in flight ^{(3) (4) (6)}.

In the violet dropwing, adults are usually seen between November and May in South Africa ⁽⁴⁾, between May and October in parts of northern Africa, and from April to October in Turkey ⁽²⁾. In the Sahara, adults of this species may be seen year-round, and in Europe they are thought to be active in all summer months ⁽²⁾.

Violet dropwing range

Originally of African origin, the violet dropwing also occurs in the Mediterranean region, and is expanding its range in southern Europe ⁽²⁾. The violet dropwing inhabits tropical Africa, where it is one of the most abundant dragonfly species ⁽²⁾, and is also found in the Middle East, parts of southern Asia, and on islands in the Indian Ocean ⁽¹⁾, including Madagascar ^{(1) (4)}.

Violet dropwing habitat

The violet dropwing can inhabit a range of vegetation types, as long as a suitable area of freshwater is available ^{(1) (2) (3)}. It is typically found near still or slow-moving water, including pools, marshes and slow-moving stretches of rivers, where there are bushes or trees nearby ⁽⁴⁾. At the edges of its range, the violet dropwing prefers warm spots such as shallow gravel pits, open lakes or lagoons ⁽²⁾.

Male violet dropwings tend to perch prominently on twigs, reeds or rocks in the sun, close to water ^{(2) (3) (4)}, and then move to the trees in the evening or when the sun is hidden behind clouds ^{(3) (4)}.

Violet dropwing status

The violet dropwing is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

Violet dropwing threats

There are not currently believed to be any significant threats to the violet dropwing, due to its widespread distribution and increasing population ^{(1) (7)}. However, this species may potentially be affected by some of the general threats faced by dragonflies, including intensive agriculture and large-scale land conversion, the destruction and modification of water bodies, over-extraction of water for irrigation, and water pollution ^{(4) (7)}. Other potential threats include global warming, which may cause water bodies to dry up during increasingly hot and dry periods ⁽⁷⁾.

Violet dropwing conservation

There are no specific conservation measures currently known to be in place for the violet dropwing. However, other conservation efforts, not directly aimed at this species, may potentially benefit its populations. For example, conservation efforts for dragonflies in Europe include research, population monitoring, appropriate legislation and the protection of key habitat sites ⁽⁷⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

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Find out more

Find out more about dragonfly 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
• Kalkman, V.J., Boudot, J-P., Bernard, R., Conze, K.J., De Knijf, G., Dyatlova, E., Ferreira, S., Jović, M., Ott, J., Riservato, E. and Sahlén, G. (2010) European Red List of Dragonflies. Publications Office of the European Union, Luxembourg. Available at:
  http://cmsdata.iucn.org/downloads/european_red_list_of_dragonflies_new.pdf

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Glossary

Abdomen

In arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (such as crabs), some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen.

Larva

Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Moult

In insects, a stage of growth whereby the hard outer layer of the body (the exoskeleton) is shed and the body becomes larger.

Nymph

Stage of insect development, similar in appearance to the adult but sexually immature and without wings. The adult form is reached via a series of moults and the wings develop externally as the nymph grows.

Territory

An area occupied and defended by an animal, a pair of animals or a colony.

Thorax

Part of the body located between the head and the abdomen in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs.

References

1. IUCN Red List (June, 2009)
   http://www.iucnredlist.org/
2. Dijkstra K-D.B. (2006) Field Guide to the Dragonflies of Britain and Europe. British Wildlife Publishing, Dorset, UK.
3. Picker, M., Griffiths, C. and Weaving, A. (2004) Field Guide to Insects of South Africa. Struik Publishers, Cape Town.
4. Samways, M.J. (2008) Dragonflies and Damselflies of South Africa. Pensoft Publishers, Bulgaria.
5. Silsby, J. (2001) Dragonflies of the World. CSIRO Publishing, Collingwood, Australia.
6. O'Toole, C. (2002) The New Encyclopedia of Insects and their Allies. Oxford University Press, Oxford.
7. Kalkman, V.J., Boudot, J-P., Bernard, R., Conze, K.J., De Knijf, G., Dyatlova, E., Ferreira, S., Jović, M., Ott, J., Riservato, E. and Sahlén, G. (2010) European Red List of Dragonflies. Publications Office of the European Union, Luxembourg. Available at:
   http://cmsdata.iucn.org/downloads/european_red_list_of_dragonflies_new.pdf