Argentine Stem Weevil (Listronotus bonariensis) The immature/larval stage of the Argentine Stem Weevil is a legless, creamy-white, active larvae up to 4mm in length. When mature the adult appears as a dark grey to black weevil with mottled grey body markings and a distinctive protruding snout, up to 3mm in length. Adult weevils emerge from overwintering sites between September and November. After mating the female weevil deposits several eggs under the leaf sheath of the host plant. Once the eggs hatch the larvae begin to feed inside the plant stem until they reach the second or third instar at which point the burrow out of the plant and drop to the ground. Once outside the plant the larva begins to feed at the base of the turf plant, ingesting plant material from the stems and crown. They are a seriou pest in turf