Effra is the daughter of a family of space hillbillies that land on planets, steal from the inhabitants, and use the land as farming round for their carnivorous flowers. The flowers yield, leaves them to devour any living creature on the planet once they blast off and find new ground. The family consists of Sybilla (Mercedes McCambridge) who is the mama, Effra who is the sexy daughter, and a mute son Keel (Dawson Palmer), who is also a werewolf.
We first see Effra while the Will Robinson (Billy Mumy) and Dr. Zachary Smith (Jonathan Harris) visit the families homestead. Effra is sitting on their porch of their spaceship, wearing a Lil' Abner type hillbilly outfit. She also has silver space opera gloves on. As Will and Dr. Smith approach, they see that the hillbillies have taken all of the items that the Robinsons have placed in a time capsule. Sybilla is less less than hospitable, and they tell the intruders to get off their land.
Later, Keel and the lovely Effra wander onto the Robinson's spaceship land. Effra flirts with Maj. Don West (Mark Goddard), which does not go over well with the jealous Judy Robinson (Marta Kristen).
Later, the Robinsons invited themselves over to the hillbillies homestead, and again are not welcomed with open arms. The hillbillies were performing a ritualistic chant among their growing plants.
The next time we see the hillbillies, the crops have greatly increased in yield. The wardrobe has also changed quite a bit. Sibilla is dressed in almost a queen like attire, while Effra has a long gown and her brunette hair is worn up in fancy curls.
Effra pays Maj. West a visit. Don is less than welcoming, and Effra mentions that she could put a spell on him, which suggests that she is some sort of a witch. She asks Will to get him a lock of Don's hair. This is obviously to be used for her spell. When Will goes to investigate closer, he is nearly swallowed by one of the flowers that has grown to giant size. Effra saves him from being devoured, and is quite cross with him when she learns that he has not fetched her the lock of hair from Maj. West.
When Will tries to warn Dr. Smith that the hillbillies are not normal, Sibilla mentions that she could easily dissolve him very easily. When Smith figures out the truth he makes his escape. The Robinsons are spraying the plants with some sort of insecticide weed eater formula, which kills them rather easily. We last see the hillbillies take off with their spacecraft, and the Robinsons and Dr. Smith count their lucky stars that they have survived.
- Sherry Jackson appeared as Pauline, the Riddler's sexy henchwoman in the 1966 back to back episodes "Death in Slow Motion" and "The Riddler's False Notion" in the TV series "Batman".