Insecticides for control of Armyworms are recommended until the first frost. Unfortunately, the damage happens so suddenly and quickly that everyone's lawns are exposed until a pest control application is applied. Your lawn needs protection! My professional insecticide Armyworm treatment is not only more potent than store-bought brands, it contains horticultural oil to help the insecticide gain entry into your lawn quicker and is more moisture-resistant.
FACTS:
I've noticed a direct correlation between freshly treated lawns and instant damage, hence requiring the use of proper fall armyworm insecticides to be used in conjunction with treatments going forward. Written articles have stated an attraction between top growth and armyworm development.
Cooler weather accelerates their life cycle process. This repeat process will happen closer to the 21-day mark than the 40-day mark. A round of insecticides applied to your lawn can residually last in your lawn up to 45 days, safeguarding it against damage.
Just like most insects, it is easier to control before any evidence of damage occurs. The early stages of the pest will eat the insecticide-laced tissue of the lawn and not develop, then die off. If you already have some damage, this will limit further damage.
If you have an already armyworm-infested lawn, the insecticide has basically stopped further damage. If your lawn has worms that are near complete stages of development, they will eat smaller worms to complete rather than the lawn. It is possible to see worms after an insect application. The application is systemic rather than contract. (Think marathon, not a sprint)
Grub control applied to your lawn earlier this year is only rated for grubs and not caterpillars. The surface insecticide applied was only good for a maximum of 30 days due to the heavy rainfalls we have had.
It is yet to be determined how much damage will be done to lawns with armyworms. While they do leave the root and crown in place and only eat leaf tissue, cool-season grass can struggle to recover as opposed to warm-season grasses found in the south. Since this is a new pest for our area, there is really not a lot of information on related topics.
According to Ohio State University, the last known outbreak was in Ohio in 1977. There is no recorded information for Western Pennsylvania from Penn State University. (other than crop damage which is a different armyworm)
*UPDATE 9/9/2021 7:19PM*
I am still seeing random armyworm activity in hit-and-miss lawn applications. While the "shock and awe" of overnight ruins of 2 weeks ago seems to have curtailed, I am still finding these caterpillars trying to eat away at lawns to get to their next stage in development.
