Proper identification of cutworms and armyworms can be difficult. Most of them hide in the soil during the day and are hard to find. The identifying characteristics mentioned here may not be as prevalent on younger specimens.

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diagram of larval stripes
ID guides often refer to patterning or color of the stripes on the larvae. If present, a MIDLINE runs down the exact center of the specimen’s DORSAL (top) surface. LATERAL lines alternate until they reach the VENTRAL (belly, lower) area.

If the specimen is a cutworm or armyworm, it will have a distinct head, 3 thoracic segments (where the true legs attach), and an abdomen. The abdomen will have 4-5 prolegs, including the anal proleg at the very posterior end. If there are more or less legs, or no distinct head, please see this page that describes other immature insects.

Consult the table below to help distinguish between winter cutworm (Noctua pronuba), variegated cutworm (Peridroma saucia), and true armyworm (Mythimna unipuncta). It is possible that growers and gardeners might encounter any or all of these species (as larvae) year round in the PNW.


Ian Maton Nature Photography: Moths of Calgary and Southern Alberta &emdash; 10223 Nutmeg (Anarta trifolii)
The Nutmeg moth ((Anarta trifolii)) PHOTO CREDIT: Ian Maton
Ian Maton Nature Photography: Moths of Calgary and Southern Alberta &emdash; 10428 Olive Green Cutworm (Dargida procincta)
Olive Green Cutworm moth ((Dargida procincta)) PHOTO CREDIT: Ian Maton

All photos used with permission.

    Green, J., et al. Winter cutworm: a new pest threat in Oregon. 2016. EM9139: p. 12.  
  Peters, A. and G.Fisher. Armyworms in grass pastures and corn in western Oregon. 2006, OSU Extension. p. 4.    
Floate, K.D., Cutworm pests of crops on the Canadian Prairies. 2017, Her Majesty the Queen in Right of Canada, represented by the Minister of Agriculture
and Agri-Food Canada: Lethbridge, Canada.
  Zuefle, M., Sweet corn larval pest identification. 2018, New York State IPM Program: Cornell University. p. 3.
    Diagram of lateral aspect of Spodoptera spp., adapted from Passoa, 1991.

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