Fall Armyworm | Vol 3, No. 15

Spodoptera frugiperda

Order: Lepidoptera
Family: Noctuidae

Last year was a big year for fall armyworms.  They caused a lot of damage, and insecticide applications, in commercial hay fields throughout the state.  They also caused heavy damage and more treatments than usual in home lawns, sports fields, golf courses, and commercial landscapes.  This photo is an example of the type of infestations that occurred last year.  Will they be back again this year?  Yes they will; this is Mississippi and we get fall armyworms every year.  Will they be as bad as they were last year?  Hopefully not, but we will have to wait and see.  How can you keep them from causing as much damage as they did last year?  Learn to scout for fall armyworms and how to recognize early signs of infestation.  Check your hay fields or bermudagrass lawns and turf regularly and be prepared to treat promptly once you detect an infestation.
 
Why are fall armyworms so sporadic and unpredictable?  Why do we have “big years,” normal years, and years when they are lower than normal?  Because they do not overwinter here.  The moths have to migrate back into the state each year from the Caribbean, Mexico and other areas of South America.  Severity and distribution of fall armyworm infestations depends on when moths arrive, how many moths arrive, where in the state they arrive, and weather conditions they experience once they get here.  In other words, it depends on how the wind blows.
 
See Extension Publication 2717, Fall Armyworms in Hayfields and Pastures for a list of recommended insecticides, application rates, pre-grazing intervals and pre-harvest intervals on forage crops.  Information on scouting and thresholds is also included.
 
See Page 8 of Extension Publication 2331, Control of Insect Pests in and around the Home Lawn, for information on do-it-yourself armyworm control in home lawns.  For smaller lawns, one of the cheapest, easiest and most convenient ways to treat is to use one of the ready-to-use hose-end applicators that contains a pyrethroid insecticide, such as permethrin, cyfluthrin, bifenthrin, or cyhalothrin.  For large lawns, one of the easiest and most convenient ways to treat is to hire a licensed commercial applicator.
 
See Pages 12 and 13 of Extension Publication 1858, Insect Control of Commercial Turf, for information on fall armyworm control in sports fields, golf courses and other commercial turf.  Before treating sports fields be sure to verify the product you plan to use is specifically labeled for use on sports fields and carefully check the re-entry interval.

Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.

The information given here is for educational purposes only.  Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.

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