invertebrate – Enviro-Mentalist

Alder Fly

Every year I learn more and more about the natural world surrounding me. I find that for every creature that I learn to identify there are at least a dozen more waiting for me.

One of the advantages of working in my current location is that I can quickly get to the riverside and look for wildlife. In the sunny days of early May (which, looking at the grey sky seem a long time ago) I went looking for the first butterflies of the year. I saw a few, but they were disturbingly small in number. However, I did come across this fly which I had never noticed before and which is apparently fairly common and widespread.

Meet the alder fly (sialis lutaria):

Not very exciting you might think, and you would probably be right – the Wildlife Trust site describes them as sluggish and apparently dead alder flies are used as fishing bait. However, I have never noticed them before even though they were everywhere on the day I went for a walk. And, look at the detail in the wings. How can you fail to be impressed by that! Apparently, they have no connection with Alder other than being found near the edge of water (where the female lays about 200 eggs) which is where Alder is commonly found. Being sluggish they spend most of their time near the water where they hatched and where they live as carnivorous larvae for a couple of years before pupating into these adults. In case you are interested they are about 2 cm in length and there are several varieties which require expert identification to differentiate them.

Damselflies

At this time of year you may notice lots of damselflies zipping about. As far as I can tell these emerge from the pond earlier than dragonflies, and, who can blame them as they make a tasty meal for their voracious cousins.

The damselfly lays it eggs in or close to water and these hatch after about a month. The nymphs then remain in the pond for one to two years before crawling up a convenient piece of vegetation and emerging from their larval case (exuvia). I think we have had at least 10 emerge from our pond in the last month. Here’s a picture I caught of a damselfy as it was emerging.

The damselfly then has to sit there as it pumps fluid to its wings and dries out before it can fly off. The time taken for this depends on the weather and one I was watching took about 3 hours in early May, but about half that time a couple of weeks later.

Damselflies are much smaller than dragonflies, and sit with their wings held in to their long slim body (thorax) unlike dragonflies which are much larger and wider and who hold their wider wings out.

This is a large red damselfy (which I think is the species that emerged from the pond in early May). Unfortunately they only tend to live for a few weeks so enjoy them whilst you can. Can you think of a better reason to put a pond in your garden than to see these fantastic creatures close-up?

For a great introduction to dragonflies and damselflies see the Leicestershire and Rutland Dragonfly Group website.