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. As Lincoln was taking Frances back to school, it was revealed that Frances had left her egg sac in the vent above Lori and Leni's room where countless spiderlings came out as Leni screams.
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.