Why is it that dogs like to roll on earthworms they find in the grass?

Answer 1

I asked my vet this years ago and what he told me was that dogs are keenly aware of scents which is why they have their nose to ground most of the time. Often times they will come across a scent in the yard that is particularly pleasing to them. They will roll in that spot to scent themselves so to speak or take that smell with them. I remember trying to find what it was in the yard that they liked but could never see anything there.

Answer 2

The same reason why they roll in the dirt, on your pillows, roll in cat or dog poop, on dead birds, on fish or anything else. They either like the smell of the stuff or they are marking the stuff with thier scent so the other animals in the area know it belongs to them.

Answer 3

the same reason they roll on dead moles, deer poop, and anything else. It smells wonderful to them! Be glad it is only rolling and only worms, mine eat dead earthworms, the ones that get baked on the sidewalk when it gets hot.

Answer 4

Ive heard they do that when they want to shake off the fleas.