Keep an eye on armyworms in fields adjacent to California rice

• By Luis Espino •

yellowstriped armyworm

Yellowstriped armyworm — photo by Whitney Cranshaw, Colorado State University;

The first set of traps were set up on April 19, and more traps are being set up as fields get ready for planting. So far, seven sites have been set up.

As you know, there are two species of armyworms that are found in rice, the true armyworm and the western yellowstriped armyworm. Surprisingly, western yellowstriped armyworm numbers have been very high in the three sites monitored so far. In the past two years of monitoring, very few of these moths were found this early.

We usually get these high numbers at the peak of armyworm flight in late June.

True armyworm numbers are low, as expected. I am not sure what the high number of western yellowstriped armyworm means, but it might be a good idea to keep an eye to see what happens in other crops around the rice area.

Dr. Luis Espino is University of California Cooperative Extension rice farming systems adviser in Butte County. He may be reached at
May 9, 2019, armyworm numbrs