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How to identify it
- The caterpillar is dark brown to black on top with a bronze sheen, three narrow yellow stripes running the length of the body and a broad white-yellow stripe down each side. It has three pairs of true legs and four pairs of abdominal prolegs and reaches about 1.5 to 1.75 inches when mature.[1][2]
- Cutworm larvae of the common turf species look very similar and are hard to tell apart; the black cutworm is dark green to gray or black with a pale stripe down the back, the granulate cutworm dark brown to gray with yellow-gray side stripes, and the variegated cutworm gray to brown with an orange side stripe.[2]
- Adult turf cutworm moths are generally gray-brown with wingspans of about 1.4 to 1.8 inches.[2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Black cutworm | Dark green to gray or black with a pale stripe down the back rather than the bronzed cutworm's bronze sheen and three yellow stripes; the black cutworm prefers closely mowed bentgrass and perennial rye.[2] |
| Variegated cutworm | Gray to brown with an orange lateral stripe; the bronzed cutworm is dark brown with a bronze sheen.[2] |
| Granulate cutworm | Dark brown to gray with yellow-gray lateral stripes but without the bronze sheen and the three narrow yellow stripes.[2] |
| White grubs | Grub damage comes from feeding below ground on turf roots, whereas cutworms clip the blades close to or at the soil surface.[1] |
Where it lives
Reported from lawns and gardens in South Dakota and listed by NC State among the four cutworms most commonly encountered on North Carolina turfgrass.[1][2]
Biology and life cycle
The bronzed cutworm has a single generation each year, and the caterpillars are active in late spring; South Dakota State found one in a garden in late May.[1]
The caterpillars are nocturnal and hide during the day, which makes them hard to find by scouting.[1]
Turf cutworms in general lay their eggs singly on the tips of leaf blades; the eggs hatch in 3 to 10 days, the larvae tunnel into the thatch or use aeration holes to reach the soil, finish development in 20 to 45 days and pupate for about two weeks.[2]
Damage and signs
- In lawns, bronzed cutworm feeding produces small brown circular patches 2 to 10 inches across, because the caterpillars clip grass blades close to or at the soil surface. Large populations can cause extensive injury, though grass normally outgrows the feeding unless it is already stressed, and unwatered lawns in dry conditions may fail to recover.[1]
- In gardens the bronzed cutworm can seriously injure young plants, clipping and killing seedlings, which matters most when cool evenings keep newly planted seedlings growing slowly.[1]
- Turf cutworms emerge at night to chew stems and blades near the soil, leaving circular dead spots, finger-sized brown crescents or ball-mark-like spots on golf greens; they are typically active in spring and fall, can strip large areas at ground level, and damage can be worse after aerification.[2]
Health risk
The sources treat the bronzed cutworm only as a lawn and garden pest and mention no effect on people.[1][2]
Control
Prevention
Scout by watching lawns for small brown spots and garden plants for leaf feeding, wilting or plants cut off near the soil, since the caterpillars themselves hide by day. For turf, NC State's general threshold of 2 to 6 larvae per square yard may indicate a need for treatment.[1][2]
Keep lawns watered: grass normally outgrows bronzed cutworm feeding unless it is stressed, and dry, unwatered lawns are the ones that may not recover.[1]
Keep them out
Protect young garden plants with rings of aluminum foil or cardboard around the stems, set one to two inches below ground and extending two to three inches above the soil, so the cutworms cannot clip the stems.[1]
Sanitation
Collecting and removing clippings from a freshly mowed area may help remove cutworm eggs, which are laid on the tips of leaf blades.[2]
Pesticides
Insecticide control of bronzed cutworms is difficult because they feed at night; dusting plants may deter feeding but washes off with rain or watering. In turf, mow 24 hours before treating, apply liquid formulations in the evening or as late in the day as possible, hold off irrigation for at least 24 hours, and treat a 20- to 30-foot buffer around greens and tees to reduce movement in from surrounding areas.[1][2]
Common questions
- What makes the small brown circles in my lawn in late spring?
- Bronzed cutworms clipping grass blades at the soil surface leave brown circular patches 2 to 10 inches across; the grass usually grows back if the lawn is watered and otherwise healthy.[1]
- How do I protect seedlings from bronzed cutworms?
- Put a collar of aluminum foil or cardboard around each stem, buried one to two inches and standing two to three inches above the soil, and check new transplants for clipped plants.[1]
- How can I recognize a bronzed cutworm?
- A dark brown caterpillar with a bronze sheen, three narrow yellow stripes along the back and a broad pale yellow stripe on each side, up to about 1.75 inches long, hiding in the thatch or soil by day.[1][2]
Sources
- South Dakota State University Extension, “Bronzed Cutworms Are Active (June 3, 2021).” extension.sdstate.edu/bronzed-cutworms-are-active (accessed 2026-11-10)
- NC State Extension, North Carolina State University, “Cutworms in Turf, NC State Extension Publications.” content.ces.ncsu.edu/cutworm-in-turf (accessed 2026-11-10)
- iNaturalist, “Nephelodes minians taxon page (order and family).” www.inaturalist.org/taxa/153076 (accessed 2026-11-10)