Diamondback moth

The diamondback moth is a common pest of brassica forage crops across Australia, particularly through spring and early summer.

Diamondback moth caterpillars can cause significant damage at all stages of crop development. Natural predators such as wasps and spiders are usually able to keep diamondback moth numbers under control.

However, at times the population may reach a size where intervention is required to prevent economic impact. Routine monitoring of spring brassica fodder crops is critical in preventing yield loss due to diamondback moth.

A simple visual inspection of a brassica crop will provide a good indication of the level of pest pressure from diamondback moths.

There are three visual observations suggesting a current or impending moth challenge may be happening:

  • Flying moths
  • Caterpillars
  • Eggs

Depending on the stage and the number of insects and intervention might be required. Other factors such as beneficial insects and rainfall may decrease the number of caterpillars in the crop.

Download the 'Diamondback moth' fact sheet

Key messages

  • Diamondback moth can cause damage to brassica forage at all stages of crop development
  • Monitor routinely to identify the presence early
  • Act fast to control insect pressure and avoid yield loss