She first appears in "Along Came a Sister", in which Lincoln volunteers to watch her for the weekend, until Leni almost kills her. Later Dad calls an exterminator to kill Frank, but in the end, is saved by Leni. After this, Lisa comments on how unusual Frank's name is, as "he" is actually a female spider, and was sluggish, as she was about to give birth soon, much to everyone's delight.
Frances is a purple tarantula, with six yellow eyes that have black pupils, and two fangs. She also has eight legs, and a small abdomen.