Pest Alert №12 — Fall Armyworms in Chicago?

It turns out at least one insect had a pretty good go this summer. Enter the fall armyworm. How bad did it get? Considered by some the worst they had seen in about 20 years (Atlanta, GA golf course superintendent). For others it was more of a wait and see (Chicago, IL).

Image 1. Fall armyworm damage in a bermudagrass rough in Atlanta. Note the damage ends where zoysiagrass begins. Armyworms feed exclusively on turfgrass foliage and obviously have preferences. Settle, Aug 24, 2021
Image 2. Fall armyworm, Spodoptera frugiperda, larvae can by identified by an inverted Y that occurs between its eyes. Settle, Aug 24, 2021

Each year we know we’ve got a big contender that will be chewing on roots and it can get bad. We preventively treat for annual white grubs of various beetles in turfgrass situations. Our timings/insecticide products for that our dialed in accordingly. Prevention of annual white grubs often works very well most years. Other insects generally do not pose as much of an issue in lawns or the fine turfgrasses grown for the game of golf. There are always a few exceptions of course. And so it was for the fall armyworm in 2021. Spodoptera frugiperda would make headlines in entomology news beginning in the southeastern US.

I was watching an early morning show on a major network broadcast from New York City in mid-September. The fall armyworm was obviously now further north and making national news. People were complaining about it in their lawns across many states including Illinois. The anchor that day had a brilliant idea. He said, “Just use artificial turf”. I turned off my TV. I disagreed.

Image 3. A treated bermudagrass lawn versus an untreated bermudagrass lawn. Fall armyworm damage stops exactly where the preventative insecticide application was made, Atlanta, GA. Settle, Sep 6, 2021
Image 4. The adult (moth) of the fall armyworm are nocturnal and isn’t a stand out in its appearance. Therefore, fall armyworm adults usually unnoticed in the landscape, Atlanta, GA. Settle, Sep 6, 2021
Image 5. Best way to scout for fall armyworms? Looking for the tell-tail signs of their egg masses works pretty darn good. Eggs of fall armyworms found on a bench at a private country club in Chicago. Settle, Sep 17, 2021

The best experts on armyworms and other insect pests will always be our regional university entomologists. I found some select posts that provide terrific information. Impactful to read in chronological order — armyworms were moving from south (NC State) to north (Univ of Wisc).

Helpful University Communications/The March of Fall Armyworms 2021

  1. Aug 5, 2021 NC State University https://ncturfbugs.wordpress.ncsu.edu/2021/08/05/fall-armyworms-alert/
  2. Aug 30, 2021 Ohio State University https://u.osu.edu/extensiongreene/2021/08/30/crop-alert-and-yard-alert-its-armyworm/
  3. Sep 9, 2021 University of Illinois http://hyg.ipm.illinois.edu/article.php?id=1251
  4. Sep, 2021 Purdue University https://turf.purdue.edu/fall-armyworms-what-next/
  5. 3. Sep 29, 2021 University of Wisconsin https://insectlab.russell.wisc.edu/2021/09/29/fall-armyworms-in-wisconsin/