(Updated 9/14/21)
Well, it’s official!
As of around 9/2/21 – Fall Armyworms have been reported throughout the entire state of Indiana. We were hoping to be spared in Northwest Indiana, but no such luck.
Actually, this seems to be an especially bad year for this pest that is currently affecting a large portion of the United States. Several articles we reviewed while writing this blog article call it the worst Fall Armyworm outbreak since 1977!
These invasive and highly destructive “worms” are actually the caterpillar / larva stage of the Armyworm Moth – which can become a real problem in the fall.
They will feed heavily on crops and grasses, including our beloved lawns!
Here at Red Hen, we’ve received photos from several customers in our area, and have confirmed they are experiencing Armyworm damage.
Adult armyworm moths are a pale brown color, with a white dot in the center of each forewing.
As a young larva, it is green in color and moves around in a looping motion.
A full-grown Armyworm larva is more of a dull-green to brown color and has alternating light and dark stripes running the length of its body. Upon reaching maturity, the larva will be about 1-1/2 inches (38 mm) long.
As the name of this creatures implies, Armyworms are known to “attack” in large groups. In these “armies”, they can affect large areas of turf, cutting it down to crown level as they go. B
Armyworm outbreaks in your turfgrass lawn will tend to be patchy and sporadic, though sometimes the feeding damage can occur on a larger scale.
The feeding damage of Armyworms can be so dramatic that may appear like sections of your lawn have disappeared overnight and you’re left with large brown spots of dead grass.
Armyworms are mostly nocturnal. The larger larva feed voraciously at night and on cloudy days. Often their presence will not be noticed until the damage is done, and it’s too late to do anything about it. Taking preventative steps before the damage occurs is a better option, but that’s quite difficult to do.
Another challenge to even being aware that Armyworms have invaded your yard is that they are hard to spot, since they can “hide” in the roots and thatch of your turfgrass. Using the “soap flush test” you can force them out to confirm if the brown spots you are seeing in your lawn are, in fact, due to some very hungry Armyworms. Here’s an article that desribes how to do a Soap Flush Test: https://blog.supersod.com/soap-flush-test-pests-including-fall-armyworm
Fortunately, unless your lawn / turfgrass is severely stressed by drought, it may recover well with proper irrigation or rainfall and proper fertilization. A healthy, properly maintained lawn goes a long way towards outcompeting weeds, insect, and disease issues.
HERE are a few links for the Experts at Purdue to learn more about Armyworms and ways you can try to control them::
- NEW Link added 9/14/21 – Purdue Landscape Report article – Fall Armyworms: What next? – https://www.purduelandscapereport.org/article/fall-armyworms-what-next/
- Purdue University Field Crops Integrated Pest Management Guide: Armyworm – https://extension.entm.purdue.edu/fieldcropsipm/insects/corn-armyworm.php
- Purdue Turfgrass Science Department Article: Armyworms Invade Indiana – https://turf.purdue.edu/armyworms-invade-indiana/
- Purdue Turfgrass Science Department’s Turfgrass Insects Guide focusing on Integrated Pest Management Strategies – https://extension.entm.purdue.edu/publications/E-61.pdf
- Michigan State University Extension, Department of Entomology – Fall Armyworm is Causing Damage to Lawns, Golf Courses and Turfgrass Areas – https://www.canr.msu.edu/news/fall-armyworm-causing-damage-to-lawns-golf-courses-and-turfgrass
