Insect of the Month - Cutworms

  Hort Snacks - March 2017
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 Causal organism: Range of species

Crops Affected: Wide host range – most vegetables including tomato, eggplant, peppers, asparagus (occasionally), carrots, cucurbits (occasionally), lettuce, corn, peas, beans, potatoes, etc.

Life Cycle:

  • Adults are moths – range in size
  • Moths lay eggs in the soil in weedy areas in late summer and into fall – overwinter as eggs or as larvae (depends on species
  • Eggs hatch and larvae emerge in spring when soils warm up
  • Pest life stage is the larvae
    • Solitary, nocturnal feeders – active at night
    • Typically stay near the soil surface during the day, near plants (subterranean)
    • Larvae curl in distinctive C-shape when disturbed
    • Larvae feed for several weeks at or near the base of plants – may reach 5 cm in length (depending on species)
  • Eggs laying and survival is reduced by cooler and wetter weather; warm and dry conditions favour development
Red-backed cutworm larva
Photos by Robert Spencer
  • Most often affect the seedlings of plants
  • Plants may have cut stems, petioles (near the soil surface) or stalks may have feeding damage
  • Numerous plants may be destroyed in a single night by a few larvae
  • Larvae curl in distinctive C-shape when disturbed – found during scouting (night time or by digging)
  • Aboveground feeding by some species may result in holes in foliage or fruit
  • Regularly check for damage, particularly in the spring
  • Search in the soil for larvae (during the day) or scout plants in the evening
  • In new fields or early in the season, scout the field edges along rough areas or in weedy areas
  • Monitor regularly for evidence of pest – apply registered controls when necessary
  • Apply controls during the late evening to ensure contact with larvae
    • Spot or area spraying may be effective
  • Replanting / reseeding crops may be necessary
  • Keep field and headlands free from weeds, as much as possible
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For more information about the content of this document, contact Robert Spencer.
This information published to the web on February 27, 2017.