There are several species of cutworms which attack lawns. The larvae is the stage that damages the turfgrass. The larvae is a large, fleshy, dull-coloured, hairless caterpillars about 1-3 inches long and varies in coloration depending upon species. In general, the cutworm caterpillars have a background color of dull gray or brown with stripes of brighter or sometimes darker colors.
The adults are dull-coloured, night flying moths and are usually only seen around lights at night in the summer months. They have a wingspan of 1 to 2 inches. The front wings have distinct scale patterns (faint lines, circles and kidney-shaped spots) which can be used to identify species.
Each cutworm species has its own life cycle. The number of generations each year depends on the species as well as the latitude or local climate. In general there are 2 or more generations. Some caterpillars overwinter as larvae or pupae, but some species cannot survive the local winters. Adults migrate south in the autumn and return on weather fronts in the spring. When the adults return, they begin to lay eggs on the tips of grass blades. Tiny caterpillars only 1 mm (1/32 inch) long hatch and begin to feed on the foliage. Caterpillars go through six or seven molts during their development. As they grow, they gradually move deeper into the thatch, carving "burrows" which they line with green excrement. Some large caterpillars stick their heads out of their burrows at night, chop off grass plants which are within reach and pull the blades back into the burrow for subsequent feeding. After feeding for two to four weeks, the caterpillars transform in the soil to pupae (cocoons), which are relatively smooth, torpedo-shaped and brown. The cutworm pupate and emerge as a moth.
The cutworms are generally a nocturnal feeder. They burrow into the thatch and emerge at night to feed on surrounding leaves and crowns. The type of damage varies, depending upon the species of cutworm damage, but in general larvae damage occurs from May through to July.
Cutworm damage is often small, and limited to a couple of small areas that often recover on their own. Occasionally, the infestations and damage are large and control is required. Here are some of the control approaches that can be taken.
If you have a history of cutworm problems, then consider overseeding with entophyte enhanced turfgrasses. Cutworm feeding on entophytic turfgrasses is deterred because of the fungal toxin within the entophytic fungi.
Beneficial nematodes can be used to suppress cutworm larvae populations.
Integrated Pest Management using Pest Controls
Cutworms are generally easy to control with pest controls because they feed on the surface of the lawn. There are several products registered for controlling cutworms.
If you suspect that you have a cutworm problem, but are unsure, contact your local Nutri-Lawn and we'll come out and take a look for you.