Common Blue Tail (Ischnura elegans)

/ / Terrestrial Inverts

Description

Species within the genus Ischnura can be found all over the world, including America.  Collectively they are known as forktails (1).  Males of the species I. elegans can often be confused with the rarer I. pumilio (2).   I. elegans has a total length between 30 and 34 mm.  The males are bronze-black, with head, thorax and abdomen base and tip marked sky blue at maturity, the young males are green.  The females have three different color forms; some mature females are very like males, but have a lilac thorax when immature.  Some females are identical to males when immature, but become brownish or greenish at maturity.  Females may have pink thorax at first and this then may become brownish or greenish (3).

Life Cycle

The nymphs are aquatic and they prey upon small aquatic insects and larvae.  The adult Ischnura elegans prey upon small flying insects (4).  The flight season is from April to late September in central and northern Europe.  There is normally only one generation per year. In the south the flight season is longer and more than one generation per annum can occur (3).

Behaviour

Male Common Blue Tails are less likely to initiate breeding practices with females of the same colour morph – it is thought that they do not recognize them as female.  The majority of males will in fact mate with females that display the most common colour morph within the population (5).

Habitat

The habituate running and standing waters.  They are tolerant of some salinity yet avoid acid habitats.  They are common within very eutrophic sites (3).

Distribution

They are spread throughout Europe (3).

References

Description written by Aino Helakallio (2009)

(1)   Ode News (1994) In Focus: The Forktails (Genus Ischnura) [online] Available:

http://www.odenews.org/onv1n1.htm [date accessed: 13/05/2009]

(2)   Centre for Environmental Data and Recording (2009) Ischnura elegans [online] Available:

http://www.habitas.org.uk/dragonflyireland/5600.htm [date accessed: 22/05/2009]

(3)   Dijkstra, K. (2006) Field guide to Dragonflies of Britain and Europe, British Wildlife Publishing, Gillingham

(4)   Natural England (2009) Blue Tailed Damselfly – Ischnura elegans [online] Available:

http://www.plantpress.com/wildlife/o135-bluetaileddamselfly.php [date accessed: 22/05/2009]

(5)   Van Gossum. H., Stocks. R., Matthysen. E., Valak. F., and De Bruyn (1999) Male choice for female colour morphs in Ischnura elegans (Ordonta, Coenagrionidae): testing the hypotheses, Animal Behaviour, 57(6): 1229-1232