I think that someone mentioned recently that 84 F was about the top. Very important to keep outdoor bins in the shade. I have expressed my fear of racoons for outdoor bins but nobody else has added anything to this idea. I think though that if I put a bin outdoors I would take pains to secure it from these critters. They are strong and smart.

Dave Nelson

Warmth
Red Worms (Eisenia fetida) tolerate bed temperatures as high as 43C (109.4F). It is best to avoid letting your worm bed temperatures go above 30C (86F). Adults of this species have been known to survive being encased in frozen material, and the cocoons are well adapted to survive sub-zero temps for extended periods. The optimal temperature range for breeding Eisenia fetida (red wigglers) is 15-20C (59-68F), yet maximum growth (weight gain) occurs closer to 25C (77F), if you want to go fishing.

steamyb, I have no idea they were so hardy. My basement is a steady 65F so maybe I need to move them downstairs!

olgap, a black bin outdoors will easily top 110F on a regular basis.

http://www.bae.ncsu.edu/topic/vermicomposting/pubs/earthworms.pdf

Thanks for your responses. I think I will give up on the bin idea. If I create a simple compost heap and add the worms, would they just disappear into the ground?

P.S. If I take a while getting back here, it is because I am not receiving notification of follow-ups. (Not in spam folder either.)

Olgap, now you have the right idea. The worms will live in and finish your compost, as long as you don't let it dry out. If you continue to add kitchen scraps to your pile, they will thrive! I currently have 3 compost piles with very active worm populations. I keep them covered in straw and burlap. They won't leave if they are composting worms.
Pete