Integrated Crop Management

Western bean cutworm flight near the end

The flight of the western bean cutworm is coming to an early close this year. Blacklight trap captures from both Boone and Woodbury counties indicate that the populations peaked on July 5 and July 9, respectively (see figures). The historical data from Woodbury County indicates that the flight started six days earlier, and peaked six days earlier, than it had any previous year in western Iowa. It appears that the flight will end considerably earlier; maybe by as much as 10 to 14 days.

What these flight data suggest is that field scouting decisions should have been made last week to coincide with peak egg laying and hatching activity. Insecticides applied this week may still kill eggs and newly hatched larvae, but the proportion of the population controlled will be relatively small compared to the overall population within the field. The best time for control of the western bean cutworm has come and gone for 2007.

Six-year blacklight captures of western bean cutworm adults from Woodbury Co., Iowa, 2002-2007.

Year First Capture Peak Capture Last Capture Total
2002 June 28 July 13 August 11 12,739
2003 July 10 August 1 August 17 244
2004 July 5 July 23 August 10 531
2005 June 28 July 13 August 10 1,328
2006 June 24 July 15 August 14 1,183
2007 June 18 July 9   -- 1,353*

*Through July 23, 2007

Adult western bean cutworm captures in a blacklight trap, Boone Co., Iowa, 2007. Peak capture on July 5. [1]Adult western bean cutworm captures in a blacklight trap, Boone Co., Iowa, 2007. Peak capture on July 5. Adult western bean cutworm captures in a blacklight trap, Woodbury Co., Iowa, 2007. Peak capture on July 9. [2]Adult western bean cutworm captures in a blacklight trap, Woodbury Co., Iowa, 2007. Peak capture on July 9.

This article originally appeared on pages 235-236 of the IC-498(20) -- July 23, 2007 issue.


Source URL:
http://www.ipm.iastate.edu/ipm/icm//ipm/icm/2007/7-23/wbc.html