the snapping of the leaves is a case of thigmonasty (undirected movement in response to touch). further stimulation of the lobe's internal surfaces by the struggling insects causes the lobes to close even tighter (thigmotropism), sealing the lobes hermetically and forming a stomach in which digestion occurs over a period of one to two weeks. leaves can be reused three or four times before they become unresponsive to stimulation, depending on the growing conditions.