Sunday, September 30, 2012

Caterpillars preparing for winter...

As things start to wind down for winter, any of the species that hope to survive the season are now making final preparations. I have been watching a reasonably large collection of Buff-Tip Moth caterpillars over the past few weeks as they furiously feed up before pupating...



They live gregariously until the final instar and will often twist around each other on a single twig, as in the photo above. Fully grown they can reach 60mm in length and look very impressive, as does the damage they can inflict on the host plant-in this case oak.

When they undergo a moult, they seem to be able to do so in the same position and more-or-less at the same time...

The remains of a mass-moult
The black spots on a bright yellow or orange background make this caterpillar very conspicuous and also of course, warn of its poisonous nature.




If that wasn't enough to deter any unsuspecting predator, it also has an unpleasant smell. The mature caterpillar has this striking yellow inverted 'Y' on its head.



Through last week the feeding became a lot more frenetic as the time neared for pupation. I've noticed when observing other species that just before pupation takes place, the feeding will become very intense. I also witnessed  how the group was dispersing, and saw several individuals strip an oak branch of its leaves in no time and would then be left dangling from what remains...


Although these caterpillars can be around until into October  this particular bunch have in fact now all pupated. This involved leaving the host plant/tree and once they reached the ground, bury themselves in the earth, just below the surface where they will spend the winter before emerging as the adult moths next springtime.

This is one of the last photographs I took before they all disappeared below ground...



This photo below demonstrates how the process begins, it was taken a few days after the caterpillars left the tree...







The whole transformation into a pupa seems to take quite a while in this species, especially compared to butterflies, which I've watched pupate in less than half an hour.

From looking as though they have died in the early stages, the next photograph shows how fantastic they look at the second stage...





Then finally, as the whole process is completed, they attain the darker colours that will help to camouflage them throughout the winter months should they be unearthed, or come to the surface for any reason...




I look forward to being able to bring you shots of the adult moths next year.


Until the next time...


1 comment:

  1. Wow! Fascinating series of shots! I especially love those colourful pupae!
    Maria

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