I was expecting a straightforward answer to the question -- why do earthworms surface after a rain? But the NY Times experts can only say they are uncomfortable underground in the rain. As if the rain is an opportunity to just get some fresh air and stretch out. Hmmm. I guess I'd think that way if I crawled in dirt tunnels all the time. Not convinced? It also says, "while they might meet other worms out there, I am not sure they are going out for that purpose."