Order Lepidoptera: Family Noctuidae
Pest description and damage The variegated cutworm is commonly found in gardens in the PNW. The larvae are black with brown and white markings and measure 0.5 to 0.75 inch long. Larval damage includes above-ground feeding on leaves and cutting plants off at the soil line. Cutworm larvae are nocturnal, and their damage easily might be attributed to slugs, but cutworms make clean cuts, while slugs rasp from the side of the plant leaving a ragged edge. Cutworms leave pellet-shaped droppings, while slug excreta are deposited as an S-shaped sludge wrapped in slime. A new invading species is the large yellow underwing moth, Noctua pronuba. The mature larvae of this species tends to be even larger and have a more voracious appetite than native cutworm species.
Biology and life cycle Cutworms may be found at various times of year. In the Puget Sound region, small cutworms are consistently found feeding at night in mid-December and January. Larvae, or the shiny red-brown, bullet-shaped pupa case, also may be unearthed while weeding in spring and early summer. Eggs are laid in patches on plants or nearby grasses.
Pest monitoring Watch plants for fecal pellets near defoliated leaves by day or search plants for larvae at night in mid-winter in milder climates.
Several predators including ground beetles feed on cutworms and it is likely parasitoids also feed on them. Encourage natural enemies of cutworms like birds, ground beetles, and spiders. Ground scratching birds may also play a role in keeping numbers low.
Control weeds, grasses, and debris in the vegetable garden that provide cover for marauding larvae. Using a flashlight at night, remove cutworm larvae by hand picking. Sort through the loose soil at the base of plants to find larvae in the daytime.
See Table 2 in:
For more information
Peterson, Merrill. 2012. PNW Moths (http://pnwmoths.biol.wwu.edu/browse/)
Rosetta, R. 2009. Cutworms. Oregon State University Nursery IPM (http://oregonstate.edu/dept/nurspest/cutworms.htm)