PestFacts WA

Native budworm moth trapping and caterpillar activity

  • Binnu
  • Usual automated and manual trapping locations
Native budworm caterpillar
Native budworm caterpillar. Photo courtesy of: DPIRD.

The trap Volunteer farmers, agronomists and Department of Primary Industries and Regional Development (DPIRD) staff have commenced weekly pheromone trapping for native budworm moths during the past week. This trapping is part of a program to monitor the annual native budworm migratory flights from eastern pastoral areas into the grainbelt and the potential risk of caterpillars to pulse and canola crops.

There was a large flight of budworm moths into the Binnu area this week with the trap there catching 441 moths. This follows 236 moths caught in the previous week. 

A Binnu farmer reports finding eleven grubs (6 grubs were 5-10mm long, 5 grubs were > 10mm) per 10 sweeps in a lupin crop following significant budworm moth flights into the area over recent weeks.

Results of this week's automated and manual trappings are available at the department’s Native budworm moth numbers captured in 2019.

A mapped view of the native budworm trap captures is available at cesar’s MothTrapVisWA page. Viewers need to select the desired trapping date range.

Trapping numbers only provide an indication of the pests’ activity and cannot be relied upon for control decisions. Only the use of a sweep net to regularly check crops can give growers confidence in the levels of budworm caterpillars present.

Native budworm moth flights are often variable and unpredictable but moths generally prefer to land in flowering crops in preference to nearby crops that are yet to flower. Native budworm moths arriving into flowering crops now may be ready to lay eggs or may feed on flower nectar and mate before becoming fertile. Eggs laid by moths at this time of the year will take at least two weeks before they grow to a size of approximately 5mm long and can be detected whilst netting crops.

Field pea, faba bean, lentil and chickpea crops are very susceptible to budworm as their pods are attractive to all sizes of caterpillars. These crops need to be checked regularly with a sweep net after the commencement of flowering with growers being prepared to apply sprays if threshold levels of caterpillars are discovered.

Serradella, lucerne, clover and annual medic seed crops may be also be attacked, pasture crops that are intending to be harvested for seed should be regularly checked for native budworm caterpillars. Last year a number of serradella seed crops were severely damaged by native budworm caterpillars.

The economic spray threshold levels will vary with crop type, grain price and control cost. These thresholds can be calculated for each grower's particular situation using a simple formula outlined at the department’s How to use the threshold table.

Detailed information on this pest can be found at the department’s Management and economic thresholds for native budworm.

For more information contact Alan Lord, Technical Officer, South Perth on +61 (0)8 9368 3758 or +61 (0)409 689 468.

Article author: Alan Lord (DPIRD South Perth).