I had a mass exodus only once, and it was very tiny tiny ones climbing up the side of the bin. They were so tiny that they dried out before they got out of the box!

My theory was that I had let the box get too wet and they were looking for a dryer spot. But, as I said, this is just a theory. Other than that, I have never had worms climb up the sides. Carmellia

When first introduced to a new environment worms will often crawl from the bin in search of more familiar territory; it's normal worm behavior. Crawl CAN be limited by keeping a light on over the bin, but this will only be effective for a relatively short time, as once they become adapted to the light it will no longer inhibit them. It usually takes nor more than a few days for worms to settle into a new bin, however, and for worm crawl to stop. The addition of compost from a backyard pile or even vermicompost from an old bin as about 1/3 of the bedding will usually help worms to settle in to a new bin immediately. Still, crawl rarely results in the loss of significant worm numbers, though it may sometimes seem otherwise.

Carmellia, you've got a nice level head on your shoulders, and do a good job of observation in your bin. Water and oxygen in the worm bin reside in the same spaces, thus when there is too much moisture that means O2 has been displaced. Saturated conditions will often send worms up the bin walls, not to avoid the moisture, but for a breath of fresh air. Adding dry bedding will usually aid in creating good air space in the bin once again.

Kelly S