Common Darter
Sympetrum striolatum (Charpentier, 1840)

Family: Libellulidae - Darters, Skimmers and Chasers

Order: Odonata (Epiprocta) - Dragonflies

Class: Insecta

Phylum: Arthropoda

Kingdom: Animalia

Red List status: Least Concern

Total length: 35-44 mm

Abdomen length: 20-30 mm

Hindwing length: 24-30 mm

Larval body length: 15.5-18 mm, but can be highly variable

Sympetrum striolatum mating wheel, illustrating male (top) and female (bottom) colouration. The greenish upper body identifies the female as an old individual. Buckinghamshire, United Kingdom. Note diagnostic features including yellow stripes on the legs, light panels on the thorax, dark wing venation and green underparts to the eyes.
Mature female common darter

DESCRIPTION

Adult: A relatively small, typical dragonfly, which may be the most commonly-encountered through much of its range. The parallel-sided abdomen has a straight, rather than a clubbed, appearance. This distinguishes it from most species in the genus, as does its larger adult size. Also unlike many of these species, there is little or no yellow at the base of the wings. Male colouration is orange to red, females are yellow when immature and become darker with age; old females are greenish. The frons forms a thick black bar in front of the eyes.  A thin yellow stripe runs down the length of each leg, and the thorax is patterned with two large yellowish panels.

 

 

Larva: Small, fairly squat, oval-shaped dragonfly larva with large bulging eyes; the front of the labial mask is typically spotted. The hind legs are very long, stretching beyond the end of the abdomen. The main diagnostic feature is the length of the spines on abdominal segment 9, which are longer than the length of the segment. Colouration is highly variable on both upper and undersides.

 

 

Similar species: The common darter shares its large range with a number of similar, related species. Small body size, the lack of a coloured patch on the hindwing and a red abdomen distinguish these species from most other darter genera. The common darter has black legs with yellow streaks, which separate it from larger Crocothemis species and from the ruddy darter (Sympetrum sanguineum), with which it may co-occur. The wings are dark-veined, a feature which reliably distinguishes it from red-veined dropwings (Trithemis), and the lower portion of the eye is green (blue in Trithemis). The large yellow panels on the sides of the thorax are unique among European Sympetrum species, and the similar vagrant darter (S. vulgatum) has black marks extending from the sides of the frons down the sides of the head (giving a 'moustached' appearance) - the frons of the common darter is straight.

The larval form is similar to that of related species. The presence of spines at the sides of body segments 8 and 9 (the final segments before the tail) distinguish it from species other than the ruddy darter, and the most reliable way to distinguish between the two is to identify adult stages from the same waterbody. Ruddy darters often prefer established, well-vegetated and sometimes seasonal, waterbodies while common darters may colonise newly-created pools. In the absence of this information, the spines on segment 9 is usually shorter than the length of the segment in the ruddy darter, but differences can be small and none of these features can be regarded as 100% reliable in distinguishing the two species.

 

HABITAT

A section of a small stream

inhabited by common darters.

Buckinghamshire, United Kingdom

Highly varied, but with a preference for still, often warm, waters, although it may colonise streams. The common darter exhibits a preference for shallow, newly-created ponds with sparse aquatic vegetation, and may also be found in very shallow ditches, bogs and seepages. The species can make use of small waterbodies, and can be found around garden ponds of any size. The common darter is able to colonise brackish waters. Larvae are often found along the bottom of a waterbody or in aquatic vegetation close

                                          to the surface.

Underside of common darter larva. Note the long spines on the final section, the broad, spoon-shaped labium and the long hind leg.
Facial details of common darter larva
Male common darter, dark form

 

 

BEHAVIOUR

In common with other darters, common darters select prominent perches, typically on waterside vegetation, from which to launch sorties to capture prey or deter others. This behaviour also serves a thermoregulatory function. Males often occur in high densities around the water's edge and defend their immediate area from rivals. Territories are not fixed, but are selected for their exposure to sunlight and so vary both over the course of the day and seasonally. Territories may be unguarded during mating activity, and so taken by subordinate males.

In areas where the species breeds in seasonal ponds, such as Algeria in the south of its range, the dragonflies will abandon the dry waterbody following emergence to forage in nearby, higher-altitude woodland before returning to breed in the autumn. In contrast to many species, common darters rarely if ever forage while patrolling for females (Corbet & Brooks, 2008).

Larvae actively hunt prey using both visual and tactile cues, although this lifestyle appears to render them susceptible to fish predation (Corbet & Brooks, 2008).

Breeding behaviour: Males patrol for females, which may advertise their receptivity by behaving conspicuously around oviposition sites and in some cases miming egg-laying behaviour, Mating begins in tandem, in which the male clasps the female behind the head and the two pair flies in this position, one dragonfly behind the other. Animals may also fly in the 'mating wheel' position, in which reproduction takes place. Females typically oviposit while in tandem and do so in open water, though often surrounded by vegetation. During this process, the male 'guides' oviposition by raising and lowering the pair's position above the water.

Emergence: Larvae emerge onto aquatic vegetation, generally low in the water. Emergence typically peaks in late summer in northern areas such as the United Kingdom, where the emergence period can extend from late April to October.

Flight season: Year-round in the Mediterranean, in southern parts of its range breeding as late as February. In northern areas, the flight season can extend from April into November, rarely December, becoming more abundant from June onwards.

 

BIOLOGY

Life cycle: In common with the common darter, the ruddy darter exhibits the unusual ability to facultatively delay development of its eggs or undergo immediate direct development, presumably as a response to different environmental conditions (Corbet & Brooks, 2008). Most other dragonfly species undergo either direct or delayed development.The larval stage completes development within a single year. Newly-emerged adults take up to three months to complete development.

 

TAXONOMY

Two forms found in the Canary Islands (S. nigrifemur) and the Atlantic coast of Ireland, Scotland and Norway (S. nigriscens) may be subspecies of S. striolatum, and are mostly distinguishable by their distribution, which does not overlap with the typical form. The former also differs in having more black on the legs, the latter by a black underside to the abdomen.

 

 

STATUS

 

This is a very common, widespread species; however, population trends are unknown and the species may be susceptible to water pollution resulting from crop production, and the loss of early-successional habitats (Clausnitzer, 2007).

 

REFERENCES

 

Asia Dragonfly

Clausnitzer, V. 2007. Sympetrum striolatum. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1

Corbet, P. and Brooks, S. 2008 Dragonflies New Naturalist Series 106, Harper-Collins, London: 456pp

Dijkstra, K-D.B. and Lewington, R. 2006 Field Guide to the Dragonflies of Britain and Europe British Wildlife Publishing: 320 pp

 Cham, S. 2007 Field Guide to the larvae and exuviae of British Dragonflies Volume 1: Dragonflies (Anisopera) The British Dragonfly Society: 76 pp.

Male common darter. Buckinghamshire, United Kingdom
Range        Description        Habitat        Behaviour        Biology        Taxonomy        Status        References
RANGE

Abundant throughout Europe although absent from northern Scandivania, becoming relatively less common in the northeast of the range. The species appears to be colonising new localities in Scotland. The species' range extends to nearby areas of North Africa and eastwards through the Russian Federation as far as China, Korea and Japan.