Latin name: Sphenophorus parvulus
Identification
The larval stage of the La Plata Weevil, commonly referred to as the billbug, is identifiable by its legless, 'C'-shaped body that extends up to 10 mm in length. This youthful stage of the pest presents a creamy-white hue with an orange-hued head. As the larvae progress to adulthood, they transform into weevils with a dark colouration ranging from brown to black. These adult billbugs are easily recognized by their elongated snouts, resembling a 'bill,' and their bent antennae. Patterns of dark brown may adorn their wing covers, and they maintain a length of up to 10 mm.
Life Cycle
The reproductive process for billbugs involves laying eggs into the stems of host plants, which become the feeding grounds for the emerging larvae. This event causes significant harm to turf grass. In New South Wales (NSW) and Queensland (QLD), Australia, adult billbugs become active starting in late August, suggesting that egg-laying likely occurs around September. Larvae hatch after fourteen days and immediately embark on feeding as they burrow toward the roots. Billbugs spend late summer to early autumn as pupae in the soil. With typically two to three cycles in a season, this pest overwinters in the young adult phase.
Symptoms and Management
Billbug larvae, as they tunnel downwards into the stem, heading for the plant's crown, can cause severe damage that often leads to plant death. The stems they leave behind appear hollow and filled with a sawdust-like substance. Plants often exhibit yellowing, which may progress to browning and death, resembling symptoms of fungal disease. High infestations can result in extensive destruction of turf areas, underscoring the need for early detection and prompt management.
There are several signs that can indicate a billbug infestation. Loose tufts of dead plants that detach easily from the ground, as the damaged stems snap at the crown, are a clear sign. Effective management of billbugs requires vigilance. A simple inspection that involves pulling on the leaf blades can reveal their presence—ease of detachment and hollow stems are key indicators. Upon confirmation, it's advisable to apply an insecticide quickly to curtail the feeding damage caused by these pests.
SOLUTIONS:
- Contact: Apparent Surround, Proforce Scarlet Trio, or Proforce Rumbler 100SC, Proforce Echelon
