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

2020 Armyworm Monitoring

Number of true armyworm moths per day:

                                                                           Week of

Trap location County 8/3 8/10 8/17 8/24 8/31
Afton and Wickman Butte 0.1 6.9 4.4 0.3 0.0
Richvale Hwy and McRae Butte 1.1 31.5 5.5 1.0 0.1
Colusa Hwy and Farris Butte 3.0 15.9 6.0 2.2 0.3
162 and Aguas Frias Butte 3.0 38.9 16.4 1.8 0.7
Gibson and Marengo Colusa 5.5 17.3 16.8 2.3 0.2
Maxwell and Four Mile Colusa 9.1 14.5 21.3 8.0 0.1
Hwy 45 and White Colusa 2.5 4.4 10.6 10.7 0.0
47 and PP Glenn 3.0 25.8 28.3 7.4 2.9
60 and P Glenn 2.2 11.7 11.3 4.1 0.7
61 and SS Glenn 2.3 7.0 14.5 1.0 0.1
162 and W Glenn 0.9 18.9 9.4 0.5 0.2
Hwy 99 and Elverta Sacramento 3.0 0.7 1.9 2.9 2.0
Pelger and Knights Sutter 1.7 1.1 0.2 0.2 0.0
Hwy 45 and 95B Yolo 8.5 6.7 24.3 12.0 2.4
Loma Rica Rd Yuba 2.1 0.8 1.2 2.0 0.3
Delta San Joaquin 0.6 0.6 2 0.0 0.0

 

Week of

Trap location County 6/1 6/8 6/15 6/23 6/29 7/6 7/13 7/20 7/27
Afton and Wickman Butte 1.5 8.3 18.0 27.5 24.0 5.3 0.9 0.0 0.0
Richvale Hwy and McRae Butte 1.3 3.3 15.6 26.0 24.0 10.0 2.8 0.5 0.0
Colusa Hwy and Farris Butte 1.1 7.6 28.1 29.0 18.4 11.9 0.2 0.1 0.1
162 and Aguas Frias Butte 1.8 8.0 15.6 17.4 23 16.0 3.0 0.5 0.5
Gibson and Marengo Colusa 0.1 1.7 15.6 15.5 13.4 12.2 0.9 0.0 0.9
Maxwell and Four Mile Colusa 0.1 3.2 9.8 14.8 12.1 28.7 0.5 0.2 0.9
Hwy 45 and White Colusa 2.1 11.1 14.4 36.4 70.7 39.7 4.2 1.0 0.2
47 and PP Glenn 1.5 7.8 23.3 31.4 24.1 20.6 4.0 0.0 0.1
60 and P Glenn 6.0 7.3 25.7 33.2 27.0 42.2 0.5 0.2 0.0
61 and SS Glenn 0.3 2.2 10.6 26.5 16.9 19.2 0.0 0.4 0.0
162 and W Glenn 8.8 14.6 22.7 26.0 18.9 11.0 1.1 0.0 0.0
Hwy 99 and Elverta Sacramento 1.9 8.0 20.0 35.3 27.8 15.3 3.3 1.4 0.1
Pelger and Knights Sutter 6.2 12.3 40.0 46.2 23.9 6.9 1.4 0.5 0.0
Hwy 45 and 95B Yolo 2.3 13.4 22.1 58.0 54.9 27.5 6.1 2.8 7.5
Loma Rica Rd Yuba 4.6 9.5 19.2 22.9 11.6 8.1 1.7 0.4 0.0
Delta San Joaquin 7.9 11.3 15.8 1.7 8.6 5.7 0.7 0.2 0.4

April and May

Trap location County 4/13 4/20 4/27 5/4 5/11 5/18 5/25
Afton and Wickman Butte - - 0.1 0.3 0.1 0.1 0.1
Richvale Hwy and McRae Butte - - - - - 0.2 0.3
Colusa Hwy and Farris Butte - - - - - 0.0 0.4
162 and Aguas Frias Butte - - - - - 0.2 0.3
Gibson and Marengo Colusa - - - - - 0.0 0.2
Maxwell and Four Mile Colusa - - - - - - 0.2
Hwy 45 and White Colusa - - - - - 0.1 0.2
47 and PP Glenn - 0.1 0.5 1.5 2.0 0.0 0.1
60 and P Glenn 1.9 1.2 1.2 3.0 0.3 0.3 2.0
61 and SS Glenn - - - 0.0 0.0 0.0 0.0
162 and W Glenn - 0.0 0.0 1.1 0.9 0.1 0.5
Hwy 99 and Elverta Sacramento - - - - - 0.0 0.0
Pelger and Knights Sutter - - 1.5 2.2 2.8 1.0 1.1
Hwy 45 and 95B Yolo - - - - - 1.6 0.2
Loma Rica Rd Yuba - - - - 0.5 0.2 0.1
Delta San Joaquin - -
- - - -
1.1

Picture1

September 9:

The number of moths has decreased in all locations. Most fields are drained or being drained right now, and the risk of armyworm injury is very low. 

This is our last update for the 2020 season. I want to thank all growers that helped us monitor armyworm in their fields, and the Rice Research Board and Corteva Agriscience for funding this project. 

Armyworm pictures

 

IMG_6382

True armyworm moth

IMG_6376

Western yellowstriped armyworm moth

IMG_6406

Third instar armyworm, a little smaller than half an inch, June 16

IMG_5114

Large armyworms, June 30

IMG_2488

Armyworm parasitoid cocoons, June 30

IMG_9402

Larva getting ready to pupate and a pupa found on July 8

IMG_5191

Typical armyworm panicle injury

Armyworm feeding

Duration and feeding capacity of armyworm instars. From Rice, Grigarick, and Way, 1982.

 

WESTERN YELLOWSTRIPED ARMYWORM

IMG_6543

Western yellowstriped armyworm feeding on redstem

IMG_6661

Western yellowstriped armyworms around alfalfa field

IMG_6672

Western yellowstriped armyworms feeding on alfalfa

IMG_6683

Western yellowstriped armyworms around alfalfa field

 

Map of Trap Locations

 

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Webmaster Email: mwquinton@ucdavis.edu