Midnight perambulations of woodlice and snake millipedes

Last Monday, as I left the house for a late night walk, a hundred or more woodlice were climbing the walls outside my front door. 

LWoodlice scaling the walls at night are a recent phenomenon. Previously, it was snake millipedes. Are they afraid they’ll be drowned in the prodigious rains of this summer?

The black snake millipedes, averaging an inch in length, are less frequent now, and never appear in the thousands that they did some years ago. I wrote about them once, suggesting that we might be on an ancient millipede migration route and that, driven by some arcane compulsion, they climbed over the house rather than crawled around it.