Here’s the latest information from UCCE Rice Farming Systems Advisor Luis Espino on armyworm in the Sacramento Valley:
Moth captures continue going down in most locations. Worm activity is similar to last week. Some fields have high number of worms, but defoliation is not severe. Worms are finishing their cycle. If you see defoliation and are thinking of a treatment, check the size of the worms. If most worms are large, they will be completing their cycle soon and the numbers will drop even without a treatment.
I found armyworm parasitoid cocoons (see picture on website). These are made by the larvae of small wasps that lay their eggs inside the armyworm. When the wasp larvae are ready to pupate, they exit the armyworm and form these cocoons. This is a good sign, shows that natural enemies are working on keeping armyworm populations in check.