Wispmothers are always female. They take the form of human (some say Elven) spirits, wreathed in mist and decaying rags. They have an affinity for frost magic, rarely appearing in more temperate climes. They are able to send out "shades", or essentially multiply, as well as smaller wisp "satellites", projectiles to attack their prey.
Wisps are small, glowing, ghostly lights. Although initially passive, these creatures later attack in tandem with the wispmother, distracting the victim and draining their energy.
Overall, Wispmothers are exceedingly difficult to defeat and if you don't take out their wisps quickly or have an Atronach that deals with them while you fight the Wispmother, then you're going to most likely be forced to retreat or you'll unfortunately be killed.