Order Lepidoptera: Family Noctuidae
Pest description and damage The variegated cutworm is commonly found in gardens. The larvae are black with brown and white markings. A new invading species is the large yellow underwing moth, Noctua pronuba, with a black stripe along the rear edge of the hind wing. 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 damage. Cutworms leave pellet-shaped droppings, while slug excreta is deposited as an S-shaped sludge wrapped in slime.
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 on 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. Using a flashlight at night, remove cutworm larvae by hand picking. Scratch the soil at the base of plants to find larvae in the daytime.
For more information
Mason, Kimberly. 2011. Another European Invader: Noctua pronuba (http://blogs.chronline.com/dailybird/?p=1293)
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)