Rhopaea canegrubs damage sugarcane at Nambour, Rocky Point and in northern New South Wales, especially in the Tweed Valley.
Damage
Rhopaea canegrubs usually cause typical 1-year type damage. Following cool autumns, some of the grubs take 2 years to develop. These grubs damage recently harvested ratoon crops.
Description
There are many different types of canegrub. It is important to know which type you have so that the best control method can be used. To identify the grub look at the hair pattern at its tail end (you will need a magnifying glass). Rhopaea canegrubs have a hair pattern of two straight rows, each with about 20 short hairs. Beetles are dark brown, about 21-30mm long, and have a coat of short, fine semi-erect hairs. Males have large feelers made up of 8 segments.
Life Cycle
Rhopaea canegrubs have a 1-year or 2-year life cycle depending in the weather. After a warm autumn, most grubs will pupate in August and emerge as beetles in late October or early November. When the autumn is cool, some of the grubs will feed through the following summer and complete a 2-year life cycle.
Beetles do no feed. Females appear not to fly and mate on the ground. Males are strong fliers and are attracted to lights.
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| Greyback Canegrub | A masters student employed by BSES studying soil distribution of the Rhopea canegrub at Condong.
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Canegrub Identification: Hold the grub with its tail-end facing you and its head pointing towards the ground. The shape, the number of rows of hair, and the number of hairs in the hair pattern (raster) are used for identification. | | ||||||||||||
