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.
NEW: A downloadable QUICK GUIDE of is available at: beav.es/Zpk.
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.
All photos used with permission.
|MORE RESOURCES FOR CUTWORM AND ARMYWORM IDENTIFICATION:|
|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.|