June 27, 2013

High numbers of true armyworm moths were reported from the black light trap at the Haskell Ag Laboratory near Concord earlier this week. Numbers declined over the past week at the South Central Ag Lab black light trap near Clay Center. None have been reported yet from the North Platte light trap. To monitor these traps go to http://entomology.unl.edu/fldcrops/lightrap.shtml

Damaging populations of armyworms were reported earlier this growing season in the eastern Corn Belt.

Armyworm moths often lay eggs in small grain fields, grass pastures, or corn fields with grassy weeds. Armyworm larvae may move out of small grain fields as they mature and damage nearby corn fields.

Be alert to the occurrence of armyworm larvae in small grains or corn. Armyworm larvae are most active at night, and hide in the soil during the day. When abundant, they may totally consume the leaves from their grassy host plants, leaving only the leaf blades. In corn a threshold suggested by Purdue University is "more than 50% of plants with armyworm feeding damage, and live armyworms less than 1.25 inches long are numerous."

Bob Wright
Extension Entomologist