"Will they come?" really depends on where you live. I live in the desert SW of the USA, and worms will not come on their own here. I have not even been able find worms in manure piles here. I have seen nightcrawlers near compost bins, but I have never seen composting worms in one.

I live in Montana and have worms in my yard. Lots of OM.
Thanks for your reply.

Hi Suzanne. I have a few other questions. 1) What do you want to accomplish with your new bin? If you want to produce much vermicompost for your garden, then you will have to add composting worms to the system or wait a LONG time for them to show up and breed to the numbers you need. Your wild herd is likely earthworms. 2) How large of a bin do you want, and what do you plan to feed with? If you have any manure piles, they will attract native composting worms and be a good feedstock. I would think any outdoor system in Montana would have to trenched into the ground and well insulated with straw, ect. in the winter. Check out redwormcomposting.com for good info on cold climate vermicomposting. Hope this helps. Pete

Suzanne ... Pete's suggestion about winterizing your outdoor pit/habitat is good. The link below has a lot about keeping the 'herd' alive in cold weather.

As to populating your pit/habitat, buying some composting worms is probably your best bet ... unless you can dig under an old fertilzer pile. That's where I got mine.[FREE being more important than YUCK!]

Also, keeping a small herd inside through the winter, will be a hedge against something going wrong with the winterizing.

Here is a link that might be useful: Winter worm composting