Nurse Roland back to health (maybe) in the story "The Little Sisters of Eluria."
Seriously (but her eyes are sparkling), Sophie says: “Yet if you were a patient, you would think it beautiful out of all measure. And you would think your nurses, the Little Sisters, the most beautiful any poor patient ever had.”
Jack looks around. “Where are they?”
“The Little Sisters don’t come out when the sun shines. And if we wish to continue our lives with the blessing, Jack, we’ll be gone our separate ways from here long before dark.”
It pains him to hear her talk of separate ways, even though he knows it’s inevitable. The pain doesn’t dampen his curiosity, however; once a coppiceman, it seems, always a coppiceman.
“Because the Little Sisters are vampires, and their patients never get well.”
- Part 3 / Chapter 21
Now clattering bugs came pouring out from under the table. They were of a sort Roland had seen before, and any doubts he might still have held about what was behind that tapestry departed at the sight of them. They were parasites, blood-drinkers, camp-followers: Grandfather-fleas. Probably not dangerous while there was a bumbler present, but of course when you spied the little doctors in such numbers, the Grandfathers were never far behind.
- Part 1 / Chapter II / Section 6
In Little Sisters of Eluria, Jenna (the only sister that is good) uses insects to heal her patients. And John Coffey (the only prisoner that is innocent) can heal too, and when he does it, some insects appear. Maybe he knows the secrets of the Little Sisters.