Cutworm

There are several species of cutworms which attack lawns, however the larvae is the stage that damages turfgrass. The larvae is a large, fleshy, dull-coloured, hairless caterpillar about 1-3 inches long and varying in colour. In general, cutworm caterpillars have a dull gray or brown background colour, with stripes of brighter or sometimes darker colours.

Cutworm adults are dull-coloured, night flying moths and are usually only seen around lights at night, during Summer. They have a wingspan of 1-2 inches and their 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. Adults migrate south in the Fall and return in Spring. When the adults return, they begin to lay eggs on the tips of grass blades. Tiny caterpillars only 1mm long hatch and begin to feed on the foliage. Caterpillars go through 6 or 7 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 2 to 4 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.