Fall Armyworms

August 21, 2007

Did someone forget to tell me that the Fall season came early this year? It is 100 degrees outside. Actually, I think someone told the Fall Army worms that it was their season, because they are here and on the march. Maybe we should rename them the Summer Armyworms. If you have a Bermuda grass or Zoysiagrass lawn then you may be aware of the presence of this pest already. To be sure, they are real pests, but take heart, they will not kill your established lawn but they make you think they did. Armyworms will eat the green right off of your lawn when the populations get heavy. Know this, you can identify them and you can control them.

People sometimes believe that the turf producers do not have to deal with all of the problems a homeowner has when it comes to having a beautiful lawn. Well let me tell you, we have to deal with all of your typical problems, except shade issues, and on a much larger scale. Below I will give you a few things to think about when it comes to dealing with armyworms. I am not going to get real scientific but just give you some plain talk about these pests.

What are armyworms?

  • Caterpillars which grow to about 1 and a half inches in length at maturity.
  • They are shades of green with white stripes running the length of both sides of their backs
  • They typically like to feed at night.

When do they appear?

  • I look for them after heavy rains in the summer
  • Typically I see them in the months of July and August
  • They are more easily seen at night while feeding on the leaves

How do I know if I have an infestation in my lawn?

  • If you began to see patches of brown grass in the lawn, this may be an indicator.
  • If you notice birds , more than usual, in your lawn, then you may want to check for worms underneath the canopy of the turf
  • Get a large coffee can and cut out both ends. Press the can firmly into the ground and fill with soapy water. Caterpillars will float to the top. If you see one or two, treatment is not essential. If you see five or six, it is time to treat.

How do I treat the infestation?

  • Go to your local garden center and look for a product called Sevin and follow the label or find a permethrin.
  • If possible it is good to mow your yard prior to applying the insecticide.
  • Apply the insecticide in the late afternoon.

Armyworms, generally, are pests of Bermuda and zoysia and do not have a great impact on St. Augustine lawns. St. Augustine lawns have a pest, the chinch bug, which can do greater harm to your lawn than what the armyworm will do to your Bermuda or zoysia. We will leave that discussion to a future article.

As a producer of turf, I always like to remind people that there is no perfect turf in the South. They are living organisms and all have challenges to face. Your environment is one factor in determining the grass that is right for your lawn and there are lots of grasses to meet different environmental factors.

Good luck and watch out for those armyworms. Thanks for visiting our web site.