Welcome to my blog

This is where I post various musings about wildlife and ecology, observations of interesting species (often invertebrates)
and bits of research that grab my attention. As well as blogging, I undertake professional ecological & wildlife surveys
covering invertebrates, plants, birds, reptiles, amphibians and some mammals, plus habitat assessment and management
. I don't work on planning applications/for developers. The pages on the right will tell you more about my work,
main interests and key projects, and you can follow my academic work here.

Thursday 26 June 2014

Little soft machine

It's been hot and sunny lately and lots of people have been watching damselflies and dragonflies, including the species that visit garden ponds. One of these is the large red damselfly Pyrrhosoma nymphula and I'd recently seen nymphs, adults and exuviae (empty skins) in and around our pond. However, I hadn't expected to see this when inspecting an exuvium attached to the emergent leaf of a water-soldier plant - a very freshly emerged, pale and soft ('teneral') adult.

Teneral P. nymphula with its exuvium
Teneral P. nymphula showing the pale colour and hardening wings.
 This is a risky time for the damselfly - it is soft, unable to fly and prone to predation. The legs will have hardened first to allow it to grip the plant and leave the evuvium (you can see they are already patterned). Body fluids are then pumped into the wings to expand them from their crumpled wing-bud shape. As you can see, that has happened here and the fluid's colour is the reason for the faint greenish tinge they have. The fluids are them pumped into the abdomen to expand it and give the body its shape. If the wings or body are impeded they may harden in the wrong shape, meaning the damselfly either dies or is unable to fly (and so starves and/or can't find a mate). Even a heavy (relatively speaking) insect can make holes in the wing membrane, as can raindrops. The damselfly's only real defence is to stay hidden - when I got close it quickly flipped behind the leaf to hide itself. As the leaf is spiny and I didn't want it to damage itself, I kept out of the way after these couple of photos were taken.

If all goes well, within an hour, the adult has dried and is likely to disperse once the flight muscles are warm. Sexual maturity may take a few days during which they stay away from aggressive mature males. After this, they join the great mating game!

Portrait of a mature P. nymphula

No comments:

Post a Comment