Photo courtesy of Alabama Cooperative Extension, Blake Layton 

A fall armyworm is found on a segment of grass. Armyworms march together, eating and exposing the roots of grass, as one large army unit.  

Army Crawl across Virginia 

Throughout Virginia lawns, unbeknown to homeowners, Army companies have taken hold. Marching from one lawn to the next, these companies aren’t made of any Soldier you may have come across before. Rather, these soldiers are worms … more specifically, Fall Armyworms. And, how they got here is a story of the perfect storm. 

Armyworms get their name for their specific and unique way of life. Adults, which are moths no bigger than your thumb with inconspicuous coloring, lay eggs in cluster masses anywhere between 100 and 200. At hatching, this cohort of siblings march together to find food. This march is so unique and so resembling soldiers, that their common name stuck.  

They are native to warmer and drier climates in the U.S., and Central and South America. While there are many, so-called “races” of armyworms, some who feed specifically on corn and others on various other grasses, it is the latter that has caught many homeowners and expert entomologists in Virginia by surprise. 

This year, dry temperatures and a perfect storm dropped these unwelcome visitors onto our doorsteps by the thousands. As hurricane Ida passed through the Gulf of Mexico into Louisiana, it paved its way inland, and with it, hundreds of thousands of adult fall armyworm moths. To move around, adult moths fly upward, not across, catching moving winds to help them fly to new locations.  

While they normally stay local, with a few managing to find their way up to Northern states like Virginia every year in mid fall, this year this race of fall armyworms had everything to survive and thrive, here. While Ida dropped torrential rainfall across the state, it also dropped hundreds of thousands of moths that were caught up in its strong winds and were carried to Virginia. This caused, what experts say, is a “blow-up,” and much earlier than anyone expected. 

These marching worms cause severe destruction of lawns, eating turf and exposing roots, ultimately killing them and costing hundreds of dollars in repairs.  

However, while their destruction may have a lasting impact, their presence is not forever. These are fragile species that are susceptible to high amounts of rain and humidity; and cold; and Virginia is not conducive to survival as cooler and wetter weather hit the state.  
But climate change is showing us that this event, while rare, may become more and more common. Areas are experiencing hotter and drier temperatures and hurricanes are stronger and forming earlier. So, for a species that has evolved to use the wind, fall armyworms might start to appear much more often.   

Tomas Nocera 
Fort Belvoir Directorate of Public Works