The term LARVA SUCCESSOR is represented by the crossword solution PUPA, which is a four-letter word. A PUPA is the stage of development between larva and adult in the life cycle of an insect. It is the stage in which the insect undergoes metamorphosis, during which it changes from a larva to an adult. During this stage, the insect's body undergoes dramatic changes, including the formation of wings and other adult features.