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As the western bean cutworm (WBC) has continued to spread across the U.S., managing the pest has become increasingly difficult.
The insect has moved from its native home in the southwestern U.S. to Iowa, Michigan and Ohio, with more recent issues coming up as far east as New York. Their rapid spread is aided by their increasing resistance to Bt hybrids with the Cry1F protein.
The tell-tale sign of damage to corn caused by WBC is gouging and sometimes they'll strip along the top of the kernels and make a white scraping-kind of damage.
“Often it's not actually the amount of corn that they’re eating that makes them a problem or pest. This opens up the corn to mold,” says Ohio State University Extension entomologist Kelley Tilmon.
During the National No-Tillage Conference last January, Tilmon shared her thoughts on the best way to combat these cutworms and protect no-till corn yields.
It’s important for growers to understand WBC life stages because this gives them a better idea of when and how to best combat it. This species of insect has one generation per year, with adults emerging in late June or early July.
Eggs, smaller than the lettering on a penny, are laid in clumps of 25-100 between July and August. They start white and turn to a tannish pink before becoming purple. Once purple, they hatch within 24-48 hours. This is the ideal time to spray a pesticide, Tilmon says.
The larvae go through 5-6 stages until…