University of California Rice On-line
University of California Rice On-line
University of California Rice On-line
University of California
University of California Rice On-line

Armyworm Monitoring

2019 Armyworm Trapping

Update June 18

The number of true armyworm moths has shot up quite a bit in several locations. True armyworm has been the problem species in the past. Western yellowstriped armyworm moths have been variable, increasing in some locations, decreasing in others, but in general, the numbers are much lower than at the beginning of the season.

First instar worms are starting to show up in fields where true armyworm catches are about 10 moths/trap/day. These are very small worms not doing any damage (see the worm on the tip of my thumb in the picture below); they hide in thick stands of rice next to levees or edges of the field. I suspect these are all true armyworm, but it is difficult to tell at this stage.


It takes about 150 degree days (Celsius) for those first instars to reach the 5th instar, which is the stage that starts heavily defoliating rice. Using average temperatures from the Durham CIMIS weather station, those small larvae should reach the 5th instar by June 28 or June 29. 

Traps June 18_Page_1
Traps June 18_Page_2
Traps June 18_Page_3
Traps June 18_Page_4

Thanks to Corteva Agriscience for helping fund the 2019 armyworm trapping network.

I'm using the FarmDog app to keep track of sampling sites and moth counts.

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