Early Season Caterpillar Update

Most of Indiana experienced cooler than normal temperatures over the last week, with good amounts of precipitation providing very good growing conditions for cool-­‐season turf. However, green-­‐up of warm-­‐season grasses has been slow, so we have a relatively mixed bag for insect development and damage. The cooler temperatures and ample rainfall should help mask insect feeding damage in cool-­‐season grasses caused by caterpillars such as black cutworm and armyworm while warm season grasses may be slow to outgrow such damage until warmer weather arrives. Warm-­‐season grasses could also be experiencing delayed green-­‐up due to the feeding activity of hunting billbug adults which seem to be out in force. Unlike the bluegrass billbugs that only cause significant damage in the larvae stage, hunting billbug adults may actually damage warm-­‐season turf, especially when green-­‐ up is slowed by cooler temperatures.

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The black cutworm risk map (above) has been updated to indicate high risk areas where larval development is likely to have reached the point where damage may be visible. Golf Course Superintendents in the entire southern half of the state should be scouting for this insect and paying attention to suspect areas on closely mowed turf.

Superintendents and lawn care professionals alike should keep an eye open for armyworms. They may be small right now, but as they develop, larger larvae can make a lawn disappear practically overnight. The most susceptible turfgrasses tend to be located adjacent to weedy or unmanaged areas, fence rows, the borders of agricultural fields and ditches where tall grasses provide excellent habitat for the adult armyworms to lay eggs. Check my previous tweet for insecticide recommendations appropriate for cutworms… the same chemistries will also be effective against armyworms.

Doug Richmond, Turf Entomologist