Coronavirus (COVID-19) update: We are currently updating information following recent Queensland and Australian Government announcements. Find assistance and support for coronavirus affected businesses and industries.

Cutworm

Several species of cutworms attack a wide range of crops in Queensland. The common name 'cutworm' comes from the way larvae sever young seedling stems at or near ground level, causing plant collapse.

Scientific name

Agrostis munda (brown cutworm)
A. infusa (Bogong moth)
A. ipsilon (black cutworm)
A. prophyricollis (variable cutworm)

Description

Both larvae and moths are active at night.

Larvae:

  • up to 50mm long
  • hairless with dark heads
  • darkish bodies, often with longitudinal lines and/or dark spots
  • curl into a 'C' shape and remain still if picked up.

Moths:

  • dull brown to black patterned wings
  • attracted to light.

May be confused with

Armyworms, helicoverpa larvae

Distribution and habitat

Widespread and sporadic.

Hosts

Attacks all field crops. Crops are at most risk during seedling and early vegetative stages.

Damage

  • Young caterpillars climb plants and skeletonise the leaves or eat small holes.
  • Older larvae commonly cut through stems at ground level and feed on the top growth of felled plants, but they may also climb to browse or cut off leaves.
  • Caterpillars nearing maturity often remain underground and chew into plants at or below ground level.
  • Early autumn egg-laying results in most damage to young cereals.

Life cycle

  • Larvae feed on host plants from hatching through to maturity.
  • Mature larvae pupate in the soil.
  • Egg-lay to adult emergence is usually 8–11 weeks, depending on species.

Monitoring and thresholds

Cutworms usually feed in the late afternoon or at night. By day they hide under debris or in the soil.

  • Check crops from emergence to establishment.
  • Look for patchy areas or where the crop appears thin.
  • Scratch away surface soil to look for larvae.

Natural enemies

Cutworms are attacked by a number of parasitoid wasp species.

Naturally occurring fungal diseases can reduce populations.

Control

If distribution is patchy, spot spraying may suffice; apply late afternoon to evening for maximum contact with the caterpillars.

Control weeds 3–4 weeks before sowing.

Further information