Luis Espino has provided an excellent update to monitoring the spread of Armyworm.
Except for a couple of locations in northern Glenn County, the number of moths trapped per day increased. Numbers were quite high in the traps at Hwy 45 and White Rd in southern Colusa County, Pelger and Knights Roads in Sutter County and Hwy 20 and Loma Rica in Yuba County.
He inspected the field at Rd 60 and P in Glenn County. This area has a history of severe armyworm infestations. He found armyworms ranging from 3rd to 5th instar. Numbers were low (10 worms in about 1 hour of searching, all were near levees and roads). Defoliation was easy to find when observing closely to the canopy, but not worth a treatment. Interestingly, this field has very low numbers in the traps.
Keep scouting, the next two weeks are critical. Last year, problems started when catches were above 15 moths per day. We are getting to this point in most locations (and past that point in the three traps mentioned earlier).
Resource for Armyworm monitoring