Are red worms or night crawlers better for a composter?
Washington County Oregon
Thank you for this easy question! Seldom are applied science questions so easily and definitively answered. Red wigglers win hands down over night crawlers.
Night crawlers are "vertical hole dwellers." They create cavities at the bottom of a vertical tunnel 1-3 feet deep. They feed by attaching their strong tail hook (setae) just inside the rim of their vertical tunnels and extending their bodies out at full length as they sweep the area within their reach for any foodstuffs they can drag into their holes. And this is why you see mounds of leaves and other detritus on bare soil - night crawlers have been stocking their pantries. Their feeding method and their strong tail hook allows them to pull themselves back into their holes when they sense vibrations of approaching foot falls. It is also the basis for the cartoon battles between robins and earthworms.
By contrast, red wigglers are "horizontal litter dwellers." They evolved to live in layers of duff or any kind of organic matter than accumulates on the surface. They cannot survive in garden soil, but rather require a rich diet of organic matter that will meet their nutritional requirements. They, too, have hooks (setae) along the lower surface of their bodies, and these are used to inch them along the feeding surface.
This contrast in how the two types of worms live makes the red wiggler ideal for containerized waste management. I don't have a specific reference for this belief, but my impression is that red wigglers eat more per body mass than night crawlers. I also suspect that red wigglers reproduce at a greater rate than night crawlers, but it's hard to observe that directly.
If you haven't read Appelhof's Worms Eat my Garbage, you should - it'll tell you everything you need to know about backyard vermicomposting. It might be at your local library. See also http://www.wormwoman.com/. I note that the website is "under construction" right now, but it's a great resource too.
Short answer: red wigglers. No question!