Cabbage centre grubs

Consultant, Sandy Biddulph (Biddulph Rural Consulting), has found small grubs causing damage to a fodder rape crop in Cootamundra, in the South West Slopes of NSW. The grubs have been identified as cabbage centre grubs (Hellula sp.). Sandy says that about one grub per plant, and characteristic feeding damage of holes in the leaves, can be seen.

The crop is reported to be struggling due to the recent weather conditions and was sown late (currently at the four-leaf stage). The damage is quite severe and chemical control is likely to be employed. Esfenvalerate is the only registered chemical for control of the cabbage centre grub in rape crops.

Sandy has also observed cabbage centre grubs attacking a fodder rape crop in Wallendbeen, also in the South West Slopes of NSW. This crop is more advanced and is not experiencing the same level of damage as the crop in Cootamundra. This paddock will be grazed rather than sprayed. Sandy says that over the years, cabbage centre grubs have only been a sporadic pest in the district.

The larvae are a cream colour with dark heads, are up to 12 mm long and have longitudinal reddish-brown stripes along the body. Sandy reports that grubs can be seen binding leaves together with webbing, which is a characteristic behaviour of the cabbage centre grub. The grubs attack leaves and flowers of brassica crops, and may tunnel into the growing points of plants. Pupation takes place within the feeding tunnels. Adult moths are about 12 mm long with light and dark brown markings, and are fast fliers.

The cabbage centre grub is common throughout summer and autumn, mainly in hot, dry weather. For this reason, it is usually only a minor pest of most brassica crops, including canola.

Cabbage centre grubs may be confused with native budworm, cabbage white butterfly, vegetable looper and diamond back moth. Click here for further information.