Plan for pests: Caterpillar management

Friday, 28 February 2020

The management of caterpillars in Australian production nurseries is crucial, with approximately 10,000 species of moths and butterflies posing a biosecurity threat to the industry. The recent detection of fall armyworm in Northern Queensland reinforces the need to be well informed on best management practices.

Caterpillars damage plants by physically removing plant tissue causing window-like holes in leaves. Though newly hatched larvae only cause minimal lower leaf damage, as they grow they consume a much greater volume of food, leaving behind larger holes, rapidly increasing the amount of damage caused.


It’s important that crops are consistently monitored in order to control any infestations and minimise the risk of the pest spreading. Caterpillar infestations are best managed if the lifecycle is broken early.

There are a number of caterpillar management recommendations that growers should consider to minimise the biosecurity threat in their production businesses.

Regular plant health inspections are strongly encouraged, allowing growers to:

  • Identify the infestation sooner
  • Keep populations under control
  • More effectively manage the incursion whilst it’s considered lower risk.

Regularly assessing the state of your crops (plants), and accurately recording observations or data is useful long-term in determining pest patterns within a particular production nursery and narrowing down future detection efforts. Growers can use these results to prioritise crop monitoring in terms of risk level, for example, by prioritising crop lines that appear more susceptible.


To help growers achieve early detection, there are several management techniques that can be implemented, including:

  • Visual inspection is a simple, yet effective way to monitor egg batches, caterpillars and overall damage. Examining a small percentage (generally 1 to 10% depending on the size of your production nursery and susceptibility of plants) of the crop with holes or unusual symptoms by hand, can be enough to reveal most moth eggs and small larvae.
  • Plant beating is a technique used to detect caterpillars that can be dislodged from plants, particularly those that are difficult to recognise through visual inspection.
  • Monitoring the application of insecticides and its impact on both the plant and pest. Doing so will help growers understand the effectiveness of the application, and better manage future outbreaks and management decisions.

Implementing passive, day-to-day management processes seeks to reduce the risk of pests in production nurseries and decrease the level of damage done by pests that are already established in crops. This could include inspecting incoming stock, managing weeds and other foreign hosts, practicing good crop hygiene techniques to avoid contamination, and regular plant maintenance.

For more information: and

The ‘Building the resilience and on-farm biosecurity capacity of the Australian production nursery industry’ (NY15002) project is funded by Hort Innovation using the nursery industry levy and funds from the Australian Government.