On Wednesday, I scouted a field with a consultant in Jeff-Davis Parish. He has recommended treatment for fall armyworm (FAW) in a number of fields in the Jeff-Davis and Allen Parish area. I have also had reports of damage from Evangeline and Vermilion Parish.
If your rice was treated with Dermacor X-100, it should be safe from damage. Otherwise, it would be wise to monitor closely for this pest. This problem is compounded by the hot and dry weather conditions – which drive the armyworms into lush, green rice fields. The consultant said he has now started to recommend a shot of Karate with the first application of newpath to control this pest. This pyrethroid application is too early for weevil management (unless you have excessive adult feeding), so they’ll have to go back with one or two more applications to control rice water weevil adults later in the season when they apply permanent flood. You can also use malathion to control FAW caterpillars in rice. The rate should be adjusted based on the size of the caterpillars, as I discussed in a previous post.
One clue that armyworms might be in your field is an abundance of cattle egrets – commonly referred to as “white birds”. These birds are attracted to the field to eat the armyworms.
I noticed that some of the FAW larvae in the field were parasitized by a wasp (eggs on the back of the larva).

Eggs on back of FAW are deposited by a wasp. The wasp larvae will hatch and then consume the caterpillar. Unfortunately, insecticides will kill the beneficial insects and the pest.
We stopped and watched the behavior for a while and it was stunning to see how quickly they can strip a leaf blade off a rice plant. I can see how they can nearly defoliate a field in a short period of time.
You can easily locate FAW larvae by sweeping in an unflooded field.

Crop consultant Mr. Augustine prefers to use a sweep net to sample for FAW caterpillars in rice. FAW caterpillars in a sweep net. Notice the wide variation in color.
We noticed a wide range of caterpillar color patterns. This is pretty common with fall armyworms.
I’m working on some diagrams that show you how to tell the species apart. I will post when they are prepared. I am curious to see which strain of FAW is infesting the rice. There are two strains – the corn and the rice strain. I’m rearing some of these caterpillars to the adult stage and will let you know what we find.