Becky Ceraul writes about an icky rainy-day hazard: "My three-year-old daughter Lily and I wonder why worms are so abundant on sidewalks ... during and after rainstorms. It's an obstacle course where we live in Owings Mills." I always assumed they emerged to avoid drowning in their holes. Not so. Earthworms can live for weeks in oxygen-rich water but risk fatal dessication if they travel overland when it's dry. So they wait for rain. We see the ones stranded on fast-drying pavement.