Monday, October 18, 2010

Into Hibernation

Yesterday I watched a wild iris larvae selecting and preparing a spot for hibernation, and then settling down. After fidgeting around on its leaf, around noon it crawled up-stem to a junction, then turned downwards at the fork, crawled another 20cm, discovered the scar created where a twig had snapped off a year back, spent some 30 mins spinning silk all over that scar, before settling down there. The total journey length was some 40cm. The larva was about 75% coloured up (turning into the uncommon grey colour form).

This first photo shows the extensive silk pad about 75% completed -

The episode was tricksy to photograph as it took place fairly high up and I needed someone else to stabilise the stem. The second, less clear and earlier photo, shows the larva twisting its head about whilst spinning and deposting silk (these guys are serial spinners of silk, by the way) -

In case you're wondering, this is Heidegger - this year's larvae are named after western philosophers (and I thought I'd start with the only one that's worth reading).
Of 16 larvae seen yesterday, 2 were heavily coloured up, 3 others were in the early stages of colouring, 3 were thinking about it, but the bulk were still in Lincoln green. They are actually a little more advanced than their counterparts this time last year, when the first larva went into hibernation on 23rd October.
And by the way, iris larvae are even more interesting and exciting to study than the adults... .

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