The immature billbug (also known as the La Plata weevil) is a legless, creamy-white ‘C’ shaped larvae with an orange head capsule, with a body up to 10mm long. When mature the larvae metamorphoses Dark brown to black weevil, with a distinctive ‘bill’ like snout, and elbowed antennae. Young adults often have dark brown striping on the wing casings, bodies up to 10mm long.
Biology and Lifecycle
Adult billbugs deposit their eggs within the plant stem, where the larvae develop and feed on the plant. It is at this stage of development that the most severe damage is inflicted to turf grass. As the larvae continue to develop, they exit the plant and begin to feed on the stem and roots. Depending on location and weather conditions billbugs generally lay their eggs during October to December. The eggs develop into larvae after 2 weeks and immediately begin feeding as they burrow their way down through the plants to roots. These insect pupae, remain in the soil from late summer to early Autumn. Billbugs have a one or possibly two year life cycle and overwinter as young adults.