Armyworm Damage: Identification and Control

Many of us were affected by an infestation of fall armyworms last fall, some worse than others. With the change of weather patterns we experienced last year, this created a desirable climate for this insect to thrive in our region. These destructive insects begin as moths that lay their eggs in the turfgrass, and then change from larvae into caterpillars. They can rapidly damage a lawn due to their tactic of marching across the lawn in great numbers to chew on the leaf tissue of the turfgrass. In many cases, the lawns turned brown for a few weeks, and once the caterpillars had left the area, the lawns seemed to recover somewhat quickly and looked rather normal. Alternatively, some were not so lucky, having massive bare spots in their lawns that did not recover, which would then require new grass seed to return to a full, lush lawn.

There are several distinguishing characteristics when it comes to identifying armyworm damage. Small brown patches are often the first indicator of armyworm damage, and the size of these patches will grow as they continue to feed on the grass. They tend to chew on the leaf tissue, without killing the growing point of the plant. By chewing up all of this live tissue, it will often shear the material off, leaving behind an almost bare soil area (See images below).

In order to control armyworms, it is necessary to apply a preventative insecticide before the eggs turn into larvae and begin munching on the leaf blades. On the other hand, an insecticide can be applied early on after initial damage as a curative approach. To help your lawn recover, make sure you are watering when necessary to encourage regrowth, as well as apply a fertilizer to stimulate more healthy growth of the turfgrass. If you suspect armyworms are damaging your lawn, don’t hesitate to give us a call.