Stephen I am not sure it is meant to be taken seriously. Simply look at the dozens of wild things going on in the book- earthworms, giant earthworms, earthquake-worms, earthworm men, and every imaginable combination of worms there seems to be. Beyond the worms, though, there are even more things not to be taken seriously at all.
Ryan The book isn't really about earthworms but more about the characters struggles and mystery of whats happening. There are several different evil creatures, giant earthworms are just one of them in the series. It's end of the world fiction so one could ask your question about anything. Just cause a book has something in it rarely means thats all there is to it. The books tone is very serious and the horror is very real. It's similar to tremors but these things are far more scary and dangerous, not your standard earthworm. I was so shocked at how serious the book was, it is pretty good. Dont let the title mislead you, it's so much more then the title suggests.