Cutworms

Cutworms are the larvae (caterpillars) of several species of night-flying moths in the family Noctuidae. The larvae are called cutworms because they cut down young plants as they feed on stems at or below the soil surface. There are also species of climbing cutworms that move up plants and feed upon foliage, buds and shoots. The adults are night-flying moths and do not cause damage. As general feeders, most cutworms attack a wide range of plants. Some common vegetable hosts include asparagus, bean, cabbage and other crucifers, carrot, celery, corn, lettuce, pea, pepper, potato, and tomato. Organic control of cutworms include:

Plastic Straws – If you have a small stand of flower seedlings you wish to protect, a time-consuming but effective method is fashioning a straw shield for each plant. Cut plastic straws into 2-inch pieces, and snip the pieces lengthwise. Slip a protective straw piece around the base of each seedling stem, inserting the lowest ½ inch of straw into the soil.

Cardboard or Plastic Collars – If your seedlings are too large for drinking straw collars, use the cardboard tubes from toilet paper to make protective collars for your plants. I find that yogurt containers with the bottoms cut out work well. Because the collars leave a margin of unprotected soil beside the plant, you may lose some plants to worms that get inside the tubes, but you’ll achieve at least 80% control.

Handpicking – If you’re a night owl, you can get out your flashlight at twilight and wait for hungry cutworms to emerge from the soil and mulch. Toss the worms into a bucket of soapy water, and add any nocturnal slugs or snails on your evening rounds as well.

Biological Control – Bacillus Thuringiensis, or BT, is a well-known biological control for all types of caterpillars. This organic powder paralyzes the intestinal tract of caterpillars when they begin to feed. Apply BT to the soil around the plants, rather than to leaves, to prevent killing the butterfly larvae you want to encourage. Reapply BT after it rains.

Parasitic Nematodes – If you’re experiencing a rainy spring season that prevents the use of BT, these conditions are optimal for parasitic nematodes. These beneficial nematodes live in the soil and appreciate moist conditions to help them migrate towards their prey. Steinernema carpocapsae and S. feltiaeare two commercially available nematodes that control cutworms.