A to Z of Pests

Lesser Grain Borer

Rhyzopertha dominica

Appearance

• Adult – 3 mm long. They have a roughened dark brown or black colouring.

Lifecycle

• The female lays between 300 and 500 eggs, singly or in clusters, in loose grain.
• The eggs hatch in a few days and the larvae bore into damaged kernels to continue growing. After pupating, the adults bite their way out.
• The life cycle takes between one and two months depending on temperature.

Habits

• Originally native to the tropics, they have spread to all parts of the world but are more common in “dirty” grain, i.e. grain dust, cracked kernels.
• The damage caused by the adult lesser grain borers may facilitate infestation by secondary pests or diseases.
• It is a strong flyer and can easily migrate to begin new infestations elsewhere.