Army worms were given their moniker for a good reason. About 40 farmers now have found out why, as an infestation of the worms spread to farms last week in Watertown, Sackets Harbor and southern Jefferson County towns including Adams, Ellisburg and Henderson.
“They’re known as army worms because they march from field to field and destroy crops,” said Michael E. Hunter, field crops educator for Cornell Cooperative Extension of Jefferson County. “We now have tens of thousands in the county, and they can destroy a field within a couple of days.”
Farmers were taken aback by the outbreak of worms here, Mr. Hunter said, which can completely devour fields of corn, grass, hay and small grains unless killed by insecticide before they grow into adults. Called true army worms, the thin brown creatures are about 1½ inches at full size and are hard to detect in fields.
The worms spread here from Western New York, where they arrived about two weeks ago after migrating from the South. They were first detected off Lake Erie and eventually spread east from Buffalo to the Hudson Valley region before migrating north.
When the worms become adults, they pupate into moths like caterpillars, Mr. Hunter said. These moths intentionally seek grassy fields to lay their eggs, avoiding other crops such as alfalfa, clover and soybeans. It takes about a week for the eggs to hatch and three weeks for the worms to grow into adults.
The batch of army worms was spotted June 5 by Mr. Hunter in a field south of Adams. The wheat and rye field had only minimal damage, however, because the small worms were only about ¾-inch long. Army worms do 80 percent of their damage during the last week of their life cycle, which is why it’s vital for farmers to scout their fields before it’s too late.
“They’re relatively easy to kill with insecticides when they’re less than an inch,” Mr. Hunter said. “That’s why it’s important for farmers to scout their fields now while they’re still in the newly hatched stage. If a farmer has never seen this before, it can be a big surprise.”
Hayfields are more vulnerable to the worms than cornfields. If farmers with corn crops treat the problem early on, damage will be limited to the leaves about the cornstalks, and the plants will be unharmed. But even 50 percent damage to a hayfield can be a costly affair for dairy farmers who depend on hay for cattle forage.
Mr. Hunter said a few hay farms already have been destroyed by the worm epidemic. A 150-acre orchard grass farm in Ellisburg, for example, was wiped out by the worms in about a week. Army worms travel slowly in packs of thousands, and some farmers in South Jefferson reported that local roads were layered with them.
For some farmers, the damage could mean financial jeopardy. A 150-acre farm with a 50 percent yield loss would lose about $23,000, based on a hay price of $150 a ton.
“If this happens at small farms, they might not have enough hay for forage to feed their cattle,” Mr. Hunter said.
He said cooler weather during the past month may have contributed to the worm outbreak because other parasites that would have combatted the population have been held back by the weather as temperatures dipped below 50 degrees the week after Memorial Day. Parasitic wasps lay eggs on the back of the army worm eggs, and when the egg hatches, the wasp gets inside the worm.
“This was bad timing because the cool weather may have taken the population (of other parasites) down and given the worms a good chance of survivorship,” he said.
On the bright side, Mr. Hunter said, the worms won’t have a chance to lay enough eggs to hatch a large second generation of larvae because most were killed by insecticides. So far, about 5,000 acres of infected farmland have been sprayed.
Although it’s not likely, another migration of worms recently found in Western New York could travel north to the region, Mr. Hunter said. Some fields already sprayed may have to be treated again if it happens.
“We may see a second introduction in about a week,” he said, “so we certainly can’t let our guard down.”
Jay M. Matteson, agricultural coordinator for the Jefferson County, said the epidemic could cost farmers thousands in operating costs. The last time an outbreak spread to the north country was in the summer of 2000, when numerous farms in Lowville were invaded by worms.
“We’re being overrun by these worms in southern Jefferson County, and they’re doing tremendous damage to our crops,” he said. “Dairy farms are already in a low price cycle for their milk and have had feed costs, so they can’t afford to get hit with an extensive loss of crops.”