There are thousands of distinct species of earthworms. Most of them have some regenerative powers, but very few can regenerate both ends. I don't recall reading about any that could "triple" if cut into 3 segments. The species we normally use for vermicomposting can't regenerate both ends, so you could've just laughed back at the mocker. There are even limits to which parts will regenerate at all. If an EF lost a few tail segments, it would probably be able to regenerate those segments assuming it was otherwise healthy. But cut it somewhere where it loses a heart or two, it'll probably just die.

It's been some time since I researched this online, so feel free to verify anything I've said.

Worms are under enough stress when you get them. I have had a couple of worms that must of gotten injured and are about an inch long. There is no room for the reproductive sections. And it is not so much about how many you get but to get them in good health and reproducing. Thus not just doubling but multiplying your worm count.

plumiebear is correct. The earthworms can regrow a tail, provided it was severed below the clitellum (that's that waistband thingy on a worm). The old tail won't regrow a head.

I suspect cutting a worm in to 3 segments would probably result in death. Maybe it'll regrow the tail end, but that's a lot to ask.

Thank you for the reassurance, everyone! I am now seeing some babies in my bin, so there really is no point to increase worm count by cruelly cutting the worms in segments (and then hinder their reproduction rate)...

tn gardening is quite right - earthworm worms can indeed regrow part of a tail,provided the rest, including the clitellum and upper worm is intact. The upper part would therefore survive but the offcut tail would soon die. So you would still have only one, very stressed worm that would be too busy getting itself back together to reproduce the normal way for some considerable time. End result - lower population growth.

Here is a link that might be useful: Working Worms

Does anyone know of a website where common worm farming myths are debunked?