Dragonfly Day

On Sunday morning I joined other members of the Lower Aire Valley (LAV) volunteers, and some members of the public, in an educational walk around Letchmire Pastures to look for and learn about dragonflies and damselflies. During amphibian and invertebrate surveys on the site, we came across many dragonfly and damselfly larvae in the water, and this was a chance to see what they were changing into. The weather was kind to us and we saw a number of different species, though these were definitely more active when the wind dropped and the sun came out.

Dragonflies are generally larger, with wider bodies and large bulbous eyes that touch in the middle. At rest, their wings are held at right angles to the body, resembling a crucifix, and in flight they are fast and powerful.  In contrast, damselflies are usually smaller and more dainty. They have a thin body, and the head is slightly squarer with separate eyes on either side of the head. Flight is brief and weak, and at rest the wings are normally held together down the back.

As well as learning about their life-cycle, I learned how vulnerable the adults are when they first emerge from the larval case (exuvia). These teneral adults have faded colours and their case is soft. They need to rest for several hours, during which their wings and case harden and they are then able to fly.  During this time they are easily damaged, so it's important not to try and catch or disturb them, for example by getting too close to take photographs, as this can injure them and cause deformities as the tissues harden. They are also very prone to predation by birds during this stage. The top photograph shows a Common Darter (Sympetrum striolatum) freshly emerged for it's exuvia (taken on a zoom lens so I didn't get too close!).

One of the most impressive dragonflies seen was at the end of the session. We saw several Emperor dragonflies (Anax imperator), the largest in the UK, protecting territory over one of the ponds. When other Emperors came too close, they would get chased off, with the dragonflies reaching amazing speeds and changing direction in the blink of an eye. When they fought, you could also hear their wings as they clashed - quite an amazing sound.

Many damselflies were seen.  One group were the Blue Tailed Damselflies (Ischnura elegans), which has a predominantly black tail but with a bright blue tip, as on the middle photograph.  There are different forms of this species, identified by the different thorax (body) colours. This one is the typical which has a blue/green thorax.

The other main group of damselflies are the 'blues'.  There are half a dozen or so species that have a series of blue and black bands on their tail and they all look very similar in flight. To identify them, they either need to be caught or photographed so that the banding patterns can be examined in closer detail. One way of telling them apart is by looking at the first black mark below the thorax/at the top of the tail, as highlighted in red in the bottom photograph. The shape of this is distinctive. Here, it resembles a mushroom which identifies this species as the Common Blue Damselfly (Enallagma cyathigerum). Others are shaped line a wine glass, a U-shape, etc.

Four species of dragonfly and damselfly were seen:

• Emperor
• Red Darter
• Four Spotted Chaser
• Common Darter
• Red Eyed Damselfly
• Banded Demoiselle
• Common Blue Damselfly
• Blue Tailed Damselfly (Typica)

In addition, skipper butterflies were abundant and cinnabar moth caterpillars were also seen grazing on ragwort. It was a very enjoyable morning.