Reuters
- Armyworms turned one woman's manicured green lawn into a dry, brown field in two days.
- The pests are common in the Southeast and are invading new regions like the Northeast and Midwest.
- The worms are worse than they've been in 20 years, but here's how you can prevent and deal with this nuisance.
- See more stories on Insider's business page.
Within two days of armyworms invading her yard, Julie Kocher's plush green lawn, which she said used to feel like a soft carpet to walk on, turned into a withered swathe of brown grass that looked like it had either caught on fire or hadn't been watered in weeks.
Armyworms got their name from the way hordes of the insects infest and decimate green lawns and crop fields seemingly overnight – and the problem might be worse this year than any other in the past two decades, according to Michael Goatley, a Virginia Tech professor.
Though Kocher treated the inch-long worms in her yard with bottles of insecticides, she could still see the pests wriggling and flopping around when she was weeding, and when she mowed the lawn, a black slime splattered over her shoes – presumably the armyworms' pulverized bodies.
The 1.5 inch-long caterpillars can devastate green fields of grass and crops quickly, and pesticides become ineffective once the worms are over a half-inch long, so it's critical to recognize and treat any infestation immediately. Here are some ways you can defend your property from these pests, according to an entomologist, a professor, and a representative from a lawn-care company.
Take steps to prevent armyworms:
- Monitor your lawn regularly for patches of brown grass, tips of grass blades that have been eaten, and birds picking at your yard (birds love eating the worms, and patches of brown grass are one of the first signs of armyworm damage), Jeff Herman, editor-in-chief of the lawn-care company LawnStarter, told Insider.
- Mix soap with water and pour it over a small swathe of your lawn to check if there are caterpillars in your yard. The bugs should rise to the top if your yard has been infested.
- Mow and water your lawn regularly, which makes the grass less attractive to the pests.
- Remove grassy weeds and thatch to make your yard inhospitable for the insects' eggs and larvae.
- Goatley recommends shutting off outdoor lights by your house at night to avoid attracting moths, which lay eggs that turn into armyworms.
What to do if you have an armyworm infestation:
- Terri Billeisen, an entomologist at North Carolina State University, recommends using a liquid pesticide from this list to kill larval-stage caterpillars.
- Herman recommends using any insecticide with halofenozide that lists armyworms among the insects it targets.
- Goatley recommends using bifenthrin, which retails at $25 a bottle and can be bought at home and garden stores, or the more effective Acelepryn, which costs around $100. While bifenthrin will kill caterpillars, Goatley said Acelepryn remains effective for a longer period of time and stops damage immediately.
- Goatley said the grass can recover on its own as long as the growing point at the base of the grass shoot is undamaged. But in other cases, people may have to re-sod, re-seed and aerate any dead patches that the worms left behind.