cremaster wriggles to find silk anchor

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  • #13510


    I saw this amazing thing yesterday. I was watching a caterpillar morph into a chrysalis. And once he had wriggled his skin right up I suddenly saw his little black stalky "foot" (cremaster) wriggling around in thin air. I thought – "oh no – he’s come detached" and was sure he was about to drop to the floor. I was holding my hand underneath to catch him. He honestly didn’t seem to be attached to the branch with anything – just a bit of wriggled-up skin between him and the branch.

    Anyway, after wriggling his cremaster for a couple of seconds it suddenly made contact with the silk anchor and locked onto it. Another wiggle and his skin fell and now he is a perfect chrysalis! I couldn’t believe it. How did he avoid falling?

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  • #19855


    Also If you notice that when a ‘pillar is making his silk dot there comes the time when he turns around and backs onto it. At 1st I thought he must somehow push that little shiny black cremaster into the dot somehow, and especially as the pillar can push quite forcefully while doing this. However there’d be no way for the skin to be able to come free if this were the case. What I’ve therefore thought they are actually doing at this point is hooking their little “claws” into the dot. I figure it this way because I can quite successfully xfer a lazy pillar who hasnt made a dot at all onto someone elses dot. Sometimes some pillars will make 2.

    Indeed it is amazing when you really observe the point when the cremaster “reaches forward” and for an instant they are hanging in the balance as it were. They can miss the dot and fall to the ground through a number of reasons but this doesnt happen that often.




    Edith (butterfly breeder in Florida) and I had a long discussion about this same thing last year. I didn’t believe it at first, but Edith told me that after the skin has worked up to the silk pad, the caterpillar/chrysalis to be will extend its cremaster, a tiny grasper, and grasp the silk pad.

    The cremaster grabs with little hooks, somewhat like Velcro. After the cremaster has grasped the pad, it will twist and turn while working the hooks deeper and deeper into the pad.

    Amazing, eh!



    I wondered this for the past year, but on watching one the other day, I suspect that they hold on the old skin (which is anchored) while it feels its way for the silk pad (this one wriggled quite a lot to get a firm grip). I suspect this because of the wriggling it did to free the old skin. I’m pretty sure it kept a couple of the prolegs in the skin holding on to the silk pad, then once attached by the cremaster, it let go of th eold skin.


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