Sherry Jackson in Lost in Space

Sherry Jackson as Effra in Lost in Space.

The episode is The Space Croppers from season 1. Original air date 1966

When a howl has Dr. Smith crying werewolf, he, for once, isn’t mistaken. An enchanted family has come to the planet to sow some crops and be on their way. The mother and daughter are enchantresses (witches, if you will) while their clumsy, tongueless lout of a son/brother is a werewolf. Smith suspects none of this. He sees them only a free ride back to Earth and begins wooing the hard-bitten, widowed mother for passage. What is not known about this family is that, once they leave, their ravenous plants left behind will consume all life on the planet.