A caterpillar feeding on mature canola pods. Sampling and control Natural mortality is often insufficient to prevent economic damage, so sampling of crops to determine the abundance of caterpillars is essential. Sweep netting a chickpea crop. Multiples of 10 sweeps should be taken in several parts of the crop. If more than ten consecutive sweeps are made, there are likely to be too many dead flowers and leaves in the sample to locate the small caterpillars easily.
Netting is most efficient in short and thin crops and less efficient in tall dense crops.
The decision of when to spray a crop needs to be considered from the time of first podding for field pea, chickpea, lentil and faba bean whereas the decision for lupin and canola can be left until pods are beginning to mature. If caterpillar numbers are below the threshold limits provided, the decision to spray should be delayed and periodic sweep net sampling continued. One well-timed spray to control native budworm caterpillars should be sufficient in most situations. The application of registered rates of synthetic pyrethroid chemicals by boomspray, aircraft or under ideal conditions by mister, will kill the caterpillars present. Sweep netting of the crop should be carried out after spraying to confirm that the required level of control has been obtained.