Thursday, 31 May 2012

Damselfly emergence, a risky business.

Emergence is the most dangerous step for a Damselfly or Dragonfly. The fully formed adult is inside the cuticle of this final larval stage and will force its way out of a split at the rear. The larva will climb up plant stems over the water or climb the bank and walk sometimes metres to emerge on another support.
Most emerge vertically but a few species emerge horizontally on rocks protruding from the water or on aquatic plants. Once the support has been chosen it makes sure it has a secure grip by flexing its legs then violently flicking the abdomen. This helps make sure there are no obstructions that may stop the wings from expanding.
The ghostly shapes of exoskeletons. The empty larval cases of already emerged damselflies.
Some species emerge overnight but the majority prefer early morning as warmer temperatures allow faster completion of the process, lessening the chance of predation by birds, ants, slugs and spiders. So when i found the specimen in the third image below at 5.10p.m. i knew there had been some sort of problem.
No hope for this individual i'm afraid.
This poor soul had somehow ended up the wrong way around and was unfortunately severely deformed with no chance of the wings expanding. Quite a few apparently end up with deformed bodies due to the cuticle not splitting fully or end up with damaged wings because of obstructions while opening them. The newly emerged adults head immediately away from the water and during the immature stage actively avoid it. The area over water is a place for sexually active and aggressive males so the soft bodied tenerals, as they are called, prefer treetops or long grasses where they can feed until they become mature.


  1. Interesting set of images John. I've not seen as many empty cases in one spot.

  2. The empty cases were all from one pond at the Rising Sun. The pond was "refurbished" by the rangers a couple of years ago. I didn't know it too well but a few people said it was a good spot for Dragonflies. Lets hope the upheaval hasn't done too much damage. I'll keep a close eye on it.