I think Perionyx Excavatus have taken over
I was on another site looking at pictures of different critters that you might find in your worm bin. Just for giggles I looked at the section on perionyx excavatus. OK, it wasn't just for giggles. It has been a long time since I have seen the distinctive banding that characterizes EFs. EFs can change their coloring, depending on what you feed them, but my worms just haven't looked right.
So, here is a partial description:
# The Perionyx excavatus lacks the alternate light & dark banding of the E. fetida.
# The Perionyx excavatus clitellum covers segments 13-17 whereas the clitellum of the Eisenia Fetida covers segments 25-30
Well, my camera doesn't take real good close ups (or it does, but I don't) but I took a few pics and tried to count the segments. My worms' clitella start at segment 13.
# The Perionyx excavatus is considerably faster than the E. fetida.
I noticed that my worms seem a little faster than when I bought them.
# The Perionyx excavatus is much thinner than the E. fetida, thus making the P. excavatus much more difficult to use as a bait worm.
My worms seem to be a bit bigger than what I remember when I bought them. Isn't a typical EF 3 1/2 inches long? I have measured mine at 5 inches long. They don't appear to be any thinner.
Well, the clitellum nails it. I'm certain I started out with EFs, but it looks like I have PEs now.
What to do? I can start over. I can decide that I'm raising PEs now, I can get some EFs and try to keep them isolated.
I hate the thought of starting over, but I really wanted to raise EFs.
And this, BTW, could account for my unexplained die off. During the winter, as a cost saving measure, I was not heating the room where the worms are kept.