These caterpillars are the larvae of some moths in the family Noctuidae. They get their name from their behavior of cutting small plants at the base of the stem. Many species exist all over the world, but large specimens are generally around 1–1.5 inches (3.8 centimeters). Since there are so many species, they come in a variety of colors and patterns, so damage is the best way to identify them.
During their first instars (periods between molting), cutworms will feed on the plant’s leaves and even the roots. Cutworms exhibit stem cutting once they become larger, and because of this behavior, they can become one of the most destructive pests in your garden, especially for young plants. They can even cut the plants from beneath the soil!
Depending on your area, cutworms are generally active spring through the fall. Eggs laid in the fall often lead to overwintering caterpillars in the soil.
You can find this family of insects in all temperate and tropical zones around the world.
Tomato plants are a favorite among several species of cutworms. Because these creatures spend a lot of time in the soil, unkempt beds create a perfect environment for them.
If you just have a few plants, then plant collars are a good place to start. To do this, place a four-inch-round piece of cardboard around the stems. For very small plants, toilet paper tubes are a great solution, especially given that cutworms can start chewing from below. These caterpillars become active at dusk and feed throughout the night. You can handpick them during that time and dispose of them at your discretion. Bt (Bacillus thuringiensis) comes in many dispersal forms and can specifically target caterpillars. Make sure to read the label for instructions and intended uses.
The moth family Noctuidae has long been regarded as the “pestiest” of the moths—many of the caterpillars are large agricultural pests. But don’t forget that the adults feed on nectar and pollen, so they are indeed vital for ecosystems.