Armyworms can be a serious pest in rice. The worms can eat the rice foliate or panicles, and cause yield reductions.

In 2015, a severe outbreak of armyworms caught rice growers by surprise, resulting in yield losses. In a 2018 survey conducted by UC Cooperative Extension, rice growers reported average yield losses in 2015 ranging from 4% to 12%. Since UCCE began a monitoring program in 2016, rice losses to armyworms have been rare, according to Luis Espino, UC Cooperative Extension rice farming systems advisor in Butte and Glenn counties.

To safeguard the rice crop against the pests, UCCE began conducting...