Earthworms can grow back their tail if you chop them in half. But if you chop them close too close to their head, and damage their hearts (yes they have more than one!) and brain then it will not grow back a tail. More often than not you will end up with two dead pieces of earthworm if you chop it in half. Please don’t do this to the poor innocent worms!
Haha as a Kilkenny man I hope not because then there would be a lot of worm deaths by my hand! The answere is that its very unlikly unless you do a lot of chopping. Say all the worms are at the surface soil and there are ten worms per meter squared. Assuming te chop is as big as the worm (area of 15cm X 1cm) you only cover a area of 15cm squared per chop. Since there are 10,000cm squared in a meter only 150cm2 of this is made of worms. That means you have a 0.015% chance of killing a worm!