Originally Posted by
funbun
Euros are larger in diameter than reds (abut the size of a pencil) and significantly longer than reds. Wider dia.+ greater length = bigger. I agree with in that they are not a lot bigger, but they are bigger.
Canadian nightcrawler a significantly bigger in every way. The problem with raising Canadian nightrcralwers is they are a true earth worm and hard to raise in captivity because they need "cold" temperatures and real, deep dirt. European nightcrawlers are not nightcrawlers at all they are a bigger cousin to the red wiggler.
If you want big, humungazoidal worms that you can raise on your own and work well in the compost layer/captivity, consider African nightcrawlers. They have the same girth of the Euro but the length near that of a Canadian. The Afros are like Euros in that they are not true earth worm, i.e., not true nightcrawlers. They are a composting worm much closer to their bantam-weight red wiggler and middle-weight Euro cousins. I'd call the Afros a middle-heavy weight worm.
I've raised both Euros and red wigglers. The Euros are bigger, and the red wigglers will out compete them. If you want to raise worms, you will have to select a worm that will be a good balance: size, reproductive ability, food consumption, climate vs. habitat, toughness, ability to live underwater, keep alive, and etc. There are a lot of factors to consider.
Most people don't know it but the "red wigglers" you're buying at bait shops are mostly likely European nightcrawlers. I haven't seen true red wigglers sold in bait shops since I was a child in the 80s. This only adds to the confusion.
Since you've raised them both yourself, you know the difference. A true red wiggler is a small, small worm. Euros are bigger. Afros are longer. Alabama Jumpers and Canadian nightcrawlers are giants. And there are even bigger worms in tropical places than you'd probably mistake for snakes. But if you can't raise them in captivity is doesn't matter if they're bigger.
I wanted to raise Afro, but have had a hard time finding them, so I went back to Euros because they were a know quantity. I know I have an environment suitable for them. A simple greenhouse will keep them warm amid winter and a lot of shade and deep bedding will keep them cool amid summer.