Tuesday, September 14, 2010

The Festival of Dead iris larvae

Last Sunday's outing (gentlemen, we must all Come Out...) in pursuit of iris was particularly baleful, producing just two dead 2nd instar larvae - in 2 hrs 30 mins of actual searching. My guess is that they'd succumbed during / after that very wet week at the end of August, effectively to a 'wet weather virus'. In fact, mortality in the wild so far this autumn seems to be unusually high - and that's after a very poor egg lay.

Has anyone else encountered larvae dying off like this, either in the wild or in captivity?

To end on a happier note, here's a recent picture of a healthy wild 3rd instar larva (note the pale horns, indicating recent skin change). Most have now changed into this instar.


The Wessex Reiver said...

This is not good Matthew. After such a good season it will be pitiful not to see the effects of your work next year, for such a short sharp wet spell last month. Courage mon brave, courage!!

irisscientist said...

Yes, I encountered the same problem ealier this year.

All of my stock (reared outdoors on sleaved, potted Sallow) were early 4th instar and were eating well and were looking nice and healthy. I went away for a long weekend, during which time my specimens were exposed to an extended period of torrential downpours. I was devistated to subsequently return home to unfortunately find all of my specimens dead. A serious lesson to be learnt from this experience.