Warm Spring Means Early Arrival, Longer Season For Nebraska Cattle Pest

By Theodore Ball

Nebraska cattle producers are already dealing with drought and a historic wildfire season. Now, a UNL entomologist is warning them about another threat that has consistently been arriving ahead of schedule.

Dave Boxler, a Nebraska Extension livestock entomologist based in North Platte, says this year's unusually warm spring pushed horn fly populations to damaging levels weeks earlier than normal.

The longer season raises economic concerns for producers across the state. Horn flies begin causing measurable losses in cattle performance once populations reach around 200 flies per animal; a threshold known as the economic injury level, which Boxler said is typically reached in late May or early June in Nebraska.

"We were seeing horn fly numbers on cattle in mid-April that were exceeding the economic injury level of 200," Boxler said. "And that was all caused by the super warm temperatures that we were experiencing."

Boxler said the trend isn't new. He's observed the horn fly emerging earlier in the spring and maintaining higher populations in the fall for several years.

"We've seen that happening now over the last five to six years because of our warming conditions in the spring," Boxler said. "And then also we're seeing higher populations later in fall because of the warming in the fall, too."