July 2017 - Banded Demoiselle

 

I love my walks along the banks of the river Yare with dog, Ben. At this time of year, the banks are covered with dense vegetation, which at times I almost have to fight my way through.  As some of this vegetation includes stinging nettles, trousers are a definite necessity.  (Ben isn't daft, he stays behind me. His nose and stomach have not got much fur to protect him. I assume from this, dogs get stung in the same way as humans!). I also recommend a long-sleeved jacket. The biting insects are sometimes prevalent, and in the case of the horsefly can be painful. However, the nature that you see is well worth the stingers and biters. There is a multitude of wild flowers and animals that can be found, all creating a magical environment.

Currently there are many Banded Demoiselles to be seen (also called Banded Agrions). These are good indicators of clean water. The males, which have metallic blue-green bodies, have a broad dark band on the outer half of each wing. The females have metallic green bodies, with wings of greenish-yellow, with no banding. They have a fluttering flight, almost like a butterfly's. They start flying in May, and continue to August. Males compete on the wing for breeding territories, near to egg-laying sites. The 'territory owner' will court any visiting female by doing a special display flight for her. After mating, the females will lay their eggs underwater on the leaves of aquatic plants; the females trap a layer of air in their wings to allow them to breathe under water. After about 2 weeks the eggs hatch into nymphs, with long 'horn-like antennae and long thin legs. These nymphs will not survive polluted water, and need muddy river bottoms in which to over winter. They are night predators firing out the lower portion of their mouths (the mask) in order to grasp passing prey. They remain in the river for about 2 years, prior to climbing up plant stems (reportedly they can climb up to 100 metres out of the water) to shed their skins and become the adult damselfly we love.

Whilst Banded Demoiselles are common in Norfolk, there is another damselfly which has coloured wings which is commonly found in the West Country and is now being recorded here. This is the damselfly called the Beautiful Demoiselle. Unlike the Banded Demoiselle the whole wings of the male are dark and metallic.

 

 

 

lingibson@bawburghvillage.co.uk

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