Moths are zeroing in on cornfields in Jefferson County, attempting to lay eggs atop the leaves branching from cornstalks. If successful, western bean cutworms will emerge about a week later and feed on kernels of corn for about a month.
The cutworm hasnt yet caused much damage to sweet corn on farms in New York, where the pest was first found in the state in Wyoming County in 2009. But the moths that spread the worms are creeping from the Midwest to the Northeast in greater numbers, especially in the north country. Jefferson County led the state last year with the highest amount collected in a trap from mid-July through September. Last year the trap, in a cornfield off County Route 145 in Sackets Harbor, caught 142 in the last week of the season and 348 overall both state records. The field is owned by Ronald C. Robbins.
This summer, moth numbers are already much higher across the county, where traps are set in Sackets Harbor, Calcium, Alexandria Bay, Evans Mills and Ellisburg. The insecticide traps are small green buckets that hang on 5-foot poles near cornstalks. Male moths fly during the night into holes in the traps, attracted by female pheromones.
Last week, the most frequented trap in Sackets Harbor captured a record-shattering 336 moths well above statistics for other regions. Even more are expected this week because the moths probably havent peaked in number, said Michael E. Hunter, a field crops expert who has been collecting data on moths for Cornell Cooperative Extension of Jefferson County since 2010. Moths usually dont reach their peak numbers here until 1,400 growing-degree days have passed; but through July 29, only 1,350 days were recorded at Watertown International Airport near Dexter.
I was hoping this was going to be our toughest week, but I think this week coming up should be the peak, Mr. Hunter said last week. And if the first moths are now hatching eggs, we should start seeing larvae in the next five to seven days.
A high volume of moths also was collected at a trap in a cornfield owned by Michael J. Gracey near Five Corners Road in Calcium, which suggests the moths are spreading at higher numbers countywide, Mr. Hunter said. Two weeks ago, 158 moths were collected. But 205 moths were found in the trap Friday morning.
Moths also have been found in traps in Lewis and St. Lawrence counties, but at lower volumes. A trap in Martinsburg drew 62 moths two weeks ago, while one in Madrid had 35.
The western bean cutworm also feeds on dry beans which inspired its name but they arent grown by farmers in the north country.
Larvae eggs have not been found on cornstalks, Mr. Hunter said, but he expects to find them soon. Farmers dont need to worry about treating their fields with insecticide, he said, unless at least 5 percent of their cornstalks are covered with egg masses. Larvae grow about 1.5 inches long, are tan colored and usually feed on corn ears for about 30 days. Because they arent cannibalistic like other worms that feed on corn, multiple bean cutworms commonly feed on the same ear to cause more damage. In early September, cutworms leave the corn ear and drop to the soil and burrow a chamber to weather the winter.
Mr. Hunter said moths are believed to have migrated here from southwest Ontario, where the presence of western bean cutworms has skyrocketed this summer and farmers are treating their fields. Wind currents across Lake Ontario likely have played a role in their migration pattern.
Some farmers in the north plant genetically modified corn that may be resistant to the bean cutworm, Mr. Hunter said. But only hybrid corn plants with the Bt protein Cry1F have the potential to control outbreaks.
The pest has been present at farms in western Nebraska since the early 1940s.
To view an informational video on the western bean cutworm posted by Tracey Baute, field crops entomologist for the Ontario Ministry of Agriculture, Food and Rural Affairs, visit http://wdt.me/LURK5p.