Mother Nature has turned against the army worms in this survival-of-the-fittest battle.
Army worms that emerged last week in hayfields in Jefferson County are being stymied by fungal disease and parasitic wasps, according to Michael E. Hunter, field crops educator for Cornell Cooperative Extension of Jefferson County. Field scouts who scoured hayfields this week discovered the population of worms has declined rapidly.
Mr. Hunter, who scouted eight fields Wednesday, found worms that previously were feeding on hay stalks were dying. He said most of the worms that were still alive were covered with eggs laid by parasitic wasps. And an entomologist from Cornell University, Ithaca, confirmed Thursday that samples of army worms found in fields were infected by fungal disease.
The worms had white, fuzzy fungus all over them, Mr. Hunter said. Others had eggs from wasps on the back of their heads. When those eggs hatch, the young wasps kill the worms. So between those two factors, it seems like Mother Nature will keep them in check.
Last summer, we had a five-week stretch of hot, dry weather that allowed worms to grow, he said. But this rain and humidity has been favorable for these diseases to come, and weve had a rapid population decline.
The recent streak of rainy weather was opportune, Mr. Hunter said, because the dying worms had grown nearly to the size at which they can damage fields. The worms do about 80 percent of their damage at full size, which is about 1½ inches long. As witnessed by north country farmers last year, the worms can speedily devour fields of hay, grass, winter wheat and small grains if theyre not killed. Some farmers lost entire hayfields to the worms last summer, while others sprayed fields with insecticide before worms could get traction.
Though farmers should continue to be vigilant for worms, Mr. Hunter said, the threat has diminished.
I think were going to pull out of it, he said.
Moths that traveled from the South originally hatched worms here in mid-May, Mr. Hunter said.