This study from Denmark may be useful.[date 2004]

Here is a link that might be useful: Cocoon cold hardiness

Thanks for the link, but the page was sorta tough to read...

Dadburnit! You're right. I thought I had found a way to enlarge the text, when first found the site, but couldn't find it this time, so who knows? sorry...

Your question is good ... but much worm 'data' is filled with opinion or myth or misinformation.

I'm not up for the experiment, but maybe someone will try freezing/thawing a few to see results. This sounds like something for a science fair project ... or even higher level investigation. With soil fertility so important to food production, seems like frozen/viable cocoons could be shipped to farmers wishing to increase worm populations[ie: soil fertility]. That's a bottom-line factor and those are the ones that usually get attention.