These damaged areas are most numerous within 30 or so feet from the green apron because the cutworms like to hide in the taller turf around the green during the day, commuting onto the green at night to feed. Cutworm caterpillars feed at night, tending to feed in a circle, as far as they can reach, with their posterior end frequently inserted in a shallow hole.

Frequently, there is a shallow hole in the center of the circle. In home lawns, even those planted to tall fescue and perennial ryegrass, damage is not as easily noticed because of the height of cut.ĭamage on greens appears as circles 2 to 3 inches in diameter where the grass blades are eaten down to the crowns. As a result, damage is heaviest on greens and other golf course areas planted to bentgrass. On Kentucky bluegrass, fewer than 10% of the larvae survive. Almost as many survive on varieties of grasses that contain endophytes. By now, populations are very high.īlack cutworm larvae grow well on creeping bentgrass, perennial ryegrass, and tall fescue, with over 80% growing up to pupate. These factors result in increasing numbers as we go through the growing season. With the advent of Doppler radar, miniaturized radio transmitters, and other technology, we now know that at least some of these species migrate south in the fall, as monarch butterflies have been known to do for decades.Īs the season progresses, additional moths migrate from more southern states, and those that have already arrived go through successive generations. It was thought that these insects, along with numerous other species, die off as cold weather arrives. Black cutworms have multiple generations per year, continuing well into the fall.

They overwinter in the southern United States, and the moths fly up into Illinois in the spring. Black cutworms are numerous on golf course greens and on some lawns throughout Illinois.

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