It has continued to surprise me that most of my hens do not seem to understand that worms are food. I think they are finally starting to get better. Elsie has taken to scratching through the dirt in their pen regularly, but for the others offering them a worm meets a look that seems to say "yuck... it's covered in dirt!"
The most exciting thing for Elsie currently is when I take the shovel into the pen. Recent heavy rain has meant that I have needed to do some clearing and moving of their dirt to allow better drainage. I also turn the dirt so that it remains soft for them to scratch. Elsie enjoys getting up to her elbows (if chickens have elbows) in mud hunting for worms.
Though they don't have a lot of dirt in their pen, which has a cement floor, the worms do seem to be breeding. I don't think there is any chance of them eating them all any time soon.