Wormigration

There's a video coming your way as soon as Joe can edit the sound (the sound is me talking, not anything to do with the worms) but I thought you might like a picture of what our wee crawlers looked like as they made their way onto fresh new worm chow. (You can see the dried old chow on the left. All the little specks are poop.) 

I needed to move them from the tissue paper (more about that later) and bribed them with chow on parchment. I'd hoped they would travel from the old food to the new, and then I could lift them up on their paper to a new spot. It mostly worked - this shot is four day old bugs (I think - they hatched over a few days) crawling on the fresh worm chow. 

I'm pretty sure these ones are second instar versions. The worms will moult (shed their skins) four times, and every time they do we say they're a different "instar". An instar is a word that just describes another phase of development in arthropods. The first instar is the first three or four days (sometimes a little longer if conditions aren't great) and then they shed their exoskeleton and and emerge with a looser skin that they can fill out. These worms are so tiny that it's really hard to tell if they've done it, but it sure looks that way to me. Don't they look so different? 

If you look closely, you can see smaller darker ones in the rear, and those look like 1st instar to me, while these bigger lighter ones with particularly light heads and black faces look like 2nd instar. 

Silkworms rest before they moult - they stay still and don't eat or move around for up to a day, and then whammo - it happens.  There was a period a while ago where I thought maybe some of them were dead, but then they weren't, so it's all coming together. 

They have little legs in the front, I think you can see them, and then back at their very bums, they have "claspers" that they can use to hold onto leaves or twigs. When they're ready to moult, they spin a little pad of silk (they can make silk right from the beginning, there are little safety lines all over the place) and hook their claspers in, and then their face falls off like a mask, and they wiggle out of their old skins. I think it will be easier to see when they're bigger. Even though they grow by 20X in the first instar, they're still only a few millimetres. 

I remain entirely fascinated. 

Questions? 

Fondly,

Stephanie. Wormkeeper.