Saturday, 16 January 2010

Species Profile: Broad-Bodied Chaser

Most dragonflies in the UK have a common name reflecting how they behave in flight. The largest are the hawkers, followed by the chasers, skimmers and darters. There are three species of chaser in the UK, one of which (the scarce chaser) is quite rare. The broad-bodied chaser (Libellula depressa) is the largest and most colourful, it's name coming from the fact that it has a very broad, flattened abdomen. The male is powder blue and the female yellow and brown, though the colours do fade with age. Both the male and female have yellow spots at the sides of the segments of the abdomen.


Male, faded with age (note that the yellow spots have faded to brown):


In 2007 the UK public were asked to help map the current distribution of the broad-bodied chaser. The results can be seen here. This species used to be confined to the south of the UK, but is now gradually expanding northwards.

Broad-bodied chasers are relatively easy to photograph compared with some other UK species as males are aggressively territorial and often return to the same perch after short flights. Females often visit water bodies when males are absent to avoid being harassed. Their preferred habitat is ponds and small lakes and they are often the first species to colonise new ponds. These photos of an adult male were taken in my garden at Frog End less than two months after we dug the pond:

The first broad-bodied chaser to emerge from our pond in 2009:

Exuvia, showing the length in cm:

Tuesday, 12 January 2010

UK sites for spotting Odonata: Askham Bog

Since Adrian was brave enough to take a trip to Askham Bog in rather less than cheerful weather I decided to blog about the bog in summer.

Askham Bog (formerly Ascam and often spelled Askam) is a Yorkshire Wildlife Trust nature reserve located on the outskirts of York, UK (close to the village of Copmanthorpe to be exact). A site of Specific Scientific Interest since 1961, the bog has attracted naturalists for over 200 years. In addition to being a botanist's dream (over 420 species having been recorded over the years) the bog is home to many species of mammals, birds and insects including a number of red data book species. A wonderful history and extensive species lists for the period 1879-1979 can be found in the book "A wood in Ascam" edited by Alastair Fitter and Clifford Smith.

Much of the reserve is as the name suggests, bog, but there are also three woods - Far Wood containing lots of old beeches and oaks, Near Wood and Middle wood being composed of younger trees such as birches and hollies and two ponds. Exmoor ponies are employed as grazers to prevent the trees from spreading too far into the bog:

The small pond, looking towards Near Wood

The big pond

According to the magazine British Wildlife (Vol 13, No. 5, 2002), 8 species of Odonata were known to be breeding at the reserve in 2002. By 2005 when I moved from York to Exeter in the South of the UK I believe this totalled at least 11, but not being particularly good at identifying damselflies I'm not sure of the exact number.

The species I've seen at the reserve are as follows:

  • Four-spotted chaser
  • Broad-bodied chaser (only seen on occasion although I have seen them breeding at the small pond)
  • Common darter
  • Ruddy darter
  • Black darter (I only saw a male once and doubt that they are breeding at the site)
  • Emperor dragonfly
  • Southern hawker
  • Brown hawker
  • Common blue damselfly
  • Blue-tailed damselfly
  • Large red damselfly
  • Beautiful demoiselle

I believe that I have also seen migrant hawkers in flight, but have no photographic evidence to back that up.

In early summer the hawkers and emperors can be seen hawking over the ponds and ovipositing in the large stretches of mud at the edge.

Female brown hawkers, ovipositing in the mud produced when the water level of the small pond drops in summer:

Female southern hawker, ovipositing in the grass next to the large pond:

Later in the summer the boardwalk around Middle Wood is laden with hundreds and hundreds of common and ruddy darters. Each time you put your foot down a few more rise up and fly further down the boardwalk, only to be disturbed again a few moments later.

A male ruddy darter:

Male black darter:

The field next to the railway line contains lots of little pondlets, which are favoured by the four-spotted chaser:

Tuesday, 22 December 2009

UK sites for spotting Odonata: Little Bradley Ponds

Little Bradley Ponds, near Bovey Tracey in Devon is a small nature reserve run by Devon Wildlife Trust. There are two large and several tiny ponds on old clay workings. The old pond:

and the new pond, created in 1991:

Despite the small size of the nature reserve (~1 ha of water, with parking limited to just 2 cars at the site with space for another 2 further up the lane), it is a nationally-important site for a number of rare species. In total it has 25 species of odonata including the scarce blue-tailed damselfly, red-eyed damselfly, hairy dragonfly, lesser emperor, downy emerald and keeled skimmer. The first Devon record of brown hawker was recorded at the new pond in 1999.

Some of the most frequently seen species are the emperor dragonfly (Anax imperator):

beautiful demoiselle (Calopteryx virgo):

golden-ringed dragonfly (Cordulegaster boltonii):

southern hawker (Aeshna cyanea):

and the four-spotted chaser (Libellula quadrimaculata):

Tuesday, 30 June 2009

What do dragonflies and damselflies eat?

I'll refer to only adult dragonflies and damselflies here - more on Odonata larvae in the near future.

The adult dragonfly is a formidable hunting insect. It uses the basket formed by its legs to catch insects while they are flying. Adult dragonflies and damselflies eat other flying insects, particularly midges and mosquitoes. They also eat mayflies, butterflies, moths, bees, bugs and smaller dragonflies and one Asian species even feeds on spiders from their webs.

Large red damselfly (Pyrrhosoma nymphula) feeding:

Monday, 22 June 2009


The insects are classified into about 32 orders and 939 families. Dragonflies and damselflies form the order Odonata (25 families). The word Odonata comes from the Greek for tooth and is a name derived using a classification devised by Fabricius. Johan Christian Fabricius (1745-1808) was a Danish entomologist and economist who classified insects based on their mouthparts, which he thought were more important than other traits like wings, because feeding provides the sustenance of life.

Entomologists have been puzzled as to why Fabricius chose the name Odonata for the dragonflies and damselflies since the mandibles of most insects are toothed and a name indicating "toothed mandibles" is no more significant for dragonflies than it would be for beetles or grasshoppers. For more information on the name Odonata see the article The significance of the dragonfly name "Odonata" by Clarence E Mickel in the Annals of the Entomological Society of America.

Front view of the head of a four-spotted chaser (Libellula quadrimaculata) showing the chewing mouthparts:

Side view of the head of a male southern hawker (Aeshna cyanea):

Sunday, 21 June 2009

Welcome to the dragonflies and damselflies blog

Welcome to the dragonflies and damselflies blog: an assorted collection of articles on topics including dragonfly and damselfly names, anatomy, biology, ecology and folklore.