They invited their neighbours to a buffet party, then explained that the neighbours were to be the buffet for the spiders. The spiders needed a lot of energy, so the Fordyces ordered pizzas for them every night.
One night, when the spiders were eating their pizzas, the Fordyces begged the spiders to let them go. The spiders were defeated by the Fourth Doctor, Romana and K9, who burned the Fordyce home. At this point Patrick and his wife were able to escape. (PROSE: Return of the Spiders)