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Caterpillars

Practical biological control, IPM and environmental pest-management knowledge.

Caterpillar pest feeding on crop foliage

Caterpillars

Overview

Caterpillars are the larval stage of moths and butterflies.

In horticultural crops they cause chewing damage to:

  • leaves
  • flowers
  • fruit
  • growing points
Silver Y caterpillar (Autographa gamma)
Silver Y caterpillar (Autographa gamma). A highly polyphagous caterpillar that feeds on a wide range of horticultural crops, vegetables and ornamentals. Photograph by abumadsen, released under CC0 1.0, via iNaturalist and Wikimedia Commons.

Commonly affected crops

Silver Y caterpillar on a leaf
Silver Y caterpillar (Autographa gamma). The larva is typically bright green with pale longitudinal stripes and moves with a characteristic looping action. Photograph by Bj.schoenmakers, released under CC0 1.0, via Wikimedia Commons.

Symptoms

Typical symptoms include:

  • holes in leaves
  • chewed leaf edges
  • frass
  • damaged flowers
  • fruit feeding
  • hidden larvae inside dense canopy

Risk conditions

Condition Risk
Warm weather High
Outdoor crop exposure High
Open vents/doors Moderate
Dense canopy Moderate
Poor inspection High

Monitoring

Inspect:

  • leaf undersides
  • crop edges
  • fruit clusters
  • flowers
  • dense canopy areas

Look for larvae, eggs and frass.

IPM approach

Useful strategies:

  • early inspections
  • removal of small infestations
  • monitoring moth activity
  • crop hygiene
  • preservation of natural enemies

Key message

Caterpillar damage is easiest to manage when larvae are found early, before they become large and hidden.

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