Archive for August 12th, 2013

12
Aug
13

Look at the Pterostigmas on that!

You can just imagine the lads at the Emerald Damselfly night out saying just that; viewing the talent dancing alluringly in the middle of the pool around their tiny pile of handbags.

Well what are Pterostigmas? They are in fact cells in the leading edge of an insects wing; in this case a dragonfly or damselfly. They are often enlarged and sometimes coloured. You can see them in this photo I took the other day of a Common Emerald Damselfly on the coast here in Norfolk.

1 Common Emerald

Compare them to the Pterostigmas on this Southern Emerald Damselfly which we also saw the other day. The Pterostigmas are clearly two tone and are an important distinguishing feature between the ‘commoner’ Common Emerald and the scarcer Southern Emerald.

2 Southern Emerald

… but even the damselflies get it wrong sometimes. As you can see this male Common has coupled up with a female Southern. Too many beers obviously.

3 Emeralds Coupled

… she eventually gave him the slip however and managed to find a male southern to hook up with.

4 Lesser Emeralds Coupled

The female then took to the vegetation at the side of the pool where she carefully sliced into the rush stem with the tip of her abdomen and laid an egg inside. Look carefully and you can see the scars on the rush where she repeated the process over and over again.

A new generation in the making.

5 Lesser Emerald Egg Laying

 

 

 

 




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