Shimat V. Joseph, a turf scientist and entomologist in the College of Agriculture and Environmental Sciences entomology department, discussed the spread of armyworms with Howstuffworks.
Armyworms are native to tropical and subtropical climates and are present across the southeastern and central western United States. They hatch closer to the equator and then move north as spring turns to summer.
“In Georgia, we usually start seeing them as a problem in turfgrass beginning late July, but in 2021, we have seen high populations beginning in late June,” Joseph explained.
“They like warm temperatures and humid conditions,” Joseph said. “[In 2021], we have all that. Some growers have complained that some common insecticides used against fall armyworms are not effective this year.”
Some caterpillar infestations can contain hundreds of caterpillars, especially if they find their favorite grass to nibble on. They like to feed on bermudagrass leaf blades and stems, common in the southeast.
“They can make the lawn from green to brown within two days. Usually, the bermudagrass recovers within three to four weeks if sufficient irrigation and nutrients are provided,” Joseph said.
Joseph laid out a plan for preventing and treating armyworm infestations.
“First, have a plan to monitor the pest,” Joseph said. “Scouting for egg masses on the structures around the lawn is a good strategy for homeowners. They also lay eggs on the trees and shrubs. The lawn may appear ragged and leaves completely stripped because of caterpillar feeding. Older larvae are easier to find than younger ones. Insecticide applications might be necessary if the population is large. Contact local university agents for insecticide recommendations.”