High Numbers of Common Armyworm Moths


Dave Shetlar reported that high numbers of common armyworm (Pseudaletia unipuncta) moths are currently being captured in black light traps.  Curtis Young also reported observing numerous adults at porch lights at least when the night temperatures were above 50F.  The caterpillars of these moths feed on grasses.  Sometimes these grasses are agricultural field crops (e.g. wheat and corn), and sometimes these grasses are turf-type grasses.  This is especially significant to golf course superintendants, athletic field managers and home owners with turf adjacent to fields of wheat.  Another aspect of this alert is there is little or no corn emerged in fields in many parts of the state and there is less winter wheat growing than in many preceding years, thus turfgrass may be more highly targeted this year.

When common armyworm caterpillars are young and tiny, they go unnoticed, but as they grew, they consume greater and greater quantities of food.  As food supplies dwindle, an infestation of common armyworms may move across turfgrass en mass, thus the name armyworm, eating everything in their path.  Turfgrasses should be monitored closely so as not to miss an infestation.  Insecticides may need to be applied as a rescue treatment to limit injury.  There have been cases where lawns disappeared overnight leaving nothing behind except bare soil.  Curtis Young has also been called in on a case where huge numbers of common armyworms were chased out of a hay field by mowing.  As they marched, they encountered an in-ground swimming pool.  Like lemmings marching to the sea, hundreds of armyworms committed mass suicide by dropping into the pool.  Their little carcasses clogged the pool filters for days.