Winter cutworm egg-laying activity has been recently reported as shown in the pictures taken on host plants as well as on non-plant structures in and around farms in Western Oregon. This insect lays its eggs in flat sheet clusters. The eggs are spherical in shape, ribbed and reticulate, and cream-colored to yellow, but darken over time. One female moth can deposit up to 2,000 eggs in her lifetime. Eggs hatch after 2 to 4 weeks, depending on the weather conditions. Field collected eggs were viable and no parasitization was noted when brought to the lab early this week.
We recommend destroying the egg masses as you encounter them in your fields or farm structures by either crushing using sharp objects or smashing to allow a promising physical/mechanical control before they get to hatch and disperse in the field and cause damage this fall.
For further information on this pest, please refer to resources below:
PNW Insect Handbook Chapter: Grass Seed-Winter Cutworm
OSU Extension Publication: Winter cutworm, A new pest threat in Oregon