Larva identification

Asked March 4, 2018, 3:11 PM EST

Hello, I found this in leaf litter in my yard ( Milwaukie ) and was hoping you could tell me what it is. Thank you!

Clackamas County Oregon

1 Response

Thank you for the image of a winter cutworm, Noctua pronuba.

“Winter Cutworm: A New Pest Threat in Oregon” explains its identification and habits. Even though this was published recently (2016), these cutworms have been in Oregon since 1999. They can be voracious pests in the garden and landscape from late summer, even through the fall and winter. These caterpillars feed at night whenever the temperature is 40F or above.

“Large Yellow Underwing: A New Cutworm in Idaho” (2009) also has images and extensive information. It’s at https://www.cals.uidaho.edu/edcomm/pdf/CIS/CIS1172.pdf.

Management in the home garden can rely on nightly search-and-destroy missions about 10 PM or so. When you find one, promptly dispatch it by flicking into soapy water; cutting in half; or stomping. Bt (Bacillus thuringiensis) applied to damaged plants according to label directions may also be helpful earlier in the fall. At this time of year, any of the caterpillars which are more than half-grown – that in your image definitely is – will not be affected.