Calls started coming in about an armyworm that was devouring lawns, pastures, meadows, and alfalfa fields across Ohio. Upon collection of larvae for identification, it was easily IDed as the fall armyworm.
The fall armyworm and a close relative, the yellow striped armyworm do not overwinter in Ohio, they must migrate into the state through the summer from the south. Apparently, both species of armyworm have been exploding down south. The adults from these southern populations were swept up in summer storm fronts and pushed north. The adults of these species have been recorded to fly up to 500 miles under their own power as well.
About 2 to 2 ½ weeks ago, egg masses were observed on many items including fence posts, signposts and insect traps used to monitor other insects. Each female moth can lay egg masses of 10-20 eggs up to 100 or more at a time. These eggs hatched in 5-7 days. The larvae (caterpillars) then dropped onto plants below and started feeding. The tiny caterpillar feeding activity was relatively unnoticeable, but now that the caterpillars are older and larger, they appear to be almost eating everything in their path including each other when the food plants run out.
This damage could continue for a couple of more weeks. Thus, if you have a yard or crop field suffering from fall armyworm activity, you may need to treat the infestation with an insecticide.
The following information is for turfgrass infestations from Dr. Dave Shetlar, Ohio State University Professor Emeritus of Entomology:
“For commercial applicators, any of the pyrethroids will work well against fall or yellow striped armyworms. Bifenthrin (Talstar and many generics), lambda-cyhalothrin (Scimitar), gamma-cyhalothrin, beta-cyfluthrin (Tempo Ultra), Permethrin, etc., are common examples. Sprays are much more effective and rapid acting compared to granules. Sprays will usually kill most of the larvae within 24 hours, but granules may take 3-5 days to achieve maximum kill. This is simply due to exposure.
For homeowners, there are many over-the-counter products. Some of the most common “name brand” products are: Ortho Bug B-Gon (bifenthrin); Ortho Lawn Insect Killer (bifenthrin); Spectricide Triazicide Insect Killer for Lawns (gamma-cyhalothrin) granule and hose-end spray; Garden Tech “Sevin” (contains zeta-cypermethrin, NOT carbaryl which used to be in these containers) granule and spray; Scotts Summerguard Lawn Food with Insect Control (bifenthrin); Bayer Complete Insect Killer for lawns (Imidacloprid plus beta-cyfluthrin) granule and spray. I’m sure there are more out there.”
Similar products are available for agricultural crops and can be found in a new joint publication from Ohio State University and Michigan State University at: https://aginsects.osu.edu/news/msu-osu-insect-ipm-guide
Additional Reading can be found at:
For correct identification and confirmation, contact a professional. Any OSU Extension Office Ag Educator will be able to assist you. Here in Greene County, email Trevor Corboy, Agriculture and Natural Resources Educator with location and a picture at firstname.lastname@example.org or Kim Hupman, Program Assistant, Horticulture at email@example.com