The Chaucer Review: An Indexed Bibliography (Vols. 1-30)

Kiessling, Nicholas K. "The Wife of Bath's Tale: D 878-881." 7 (1972): 113-16.
The reference to friars as those who have driven incubi out of the countryside does not insult the Friar's virility. Women who met with incubi did not always become pregnant, though the outcome was always uncomfortable. Since the Wife of Bath shows a woman's dishonor merely as a mistake, the reference to the incubi suggests that she is more disturbed by their violence toward women.

Yamamoto, Dorothy. "'Noon oother incubus but he': Lines 878-81 in the Wife of Bath's Tale." 28 (1994): 275-78.
In medieval tradition meeting with an incubus resulted sometimes in pregnancy, but often in violence, as the story of a priest's daughter who meets an incubus in An Alphabet of Tales shows. The most likely meaning of the Wife's reference in lines 878-81 of her tale is that the incubi can do serious physical harm to women.