Livestock producers and home gardeners seeing bare patches in pastures and leafless stems where their thyme had been share a common foe this summer: grasshoppers and fall armyworms.
As food supplies continue to dry up, grasshoppers and fall armyworms are eager to eat what’s left – carefully nurtured home gardens and irrigated fields destined for haying.
Grasshoppers can consume up to 50 percent of their body weight in forage each day. By comparison, cattle consume about 2.5 percent of their body weight each day.
“In other words, 50 pounds of grasshoppers would eat about as much as a full-grown cow,” said Kelly Loftin, Extension entomologist for the University of Arkansas Division of Agriculture. “To make matters worse, grasshoppers compete directly with livestock because they prefer to eat on the most desirable forage plants.”
The fact that they’re highly mobile doesn’t help livestock either. “Grasshoppers will fly a considerable distance in search of suitable food.”
The hot, dry weather has also favored the grasshoppers by suppressing the fungi that usually help reduce grasshopper populations.
“In some situations, insecticide application can be a viable option,” Loftin said, adding that
“grasshoppers are difficult to control, particularly the large ones.”
Growers who are considering an insecticide application should wait until population densities hit 10 grasshoppers per square yard or “spot treat areas where a large number of grasshopper nymphs are observed. This technique can reduce grasshopper numbers because newly hatched nymphs remain concentrated in the hatching areas for some time.”
Despite their name, fall armyworms have already been spotted in midsummer. Loftin received his first call about the insect on July 21 from Sharp County, where a field had eight worms per square foot, well above the treatment thresholds of three worms per square foot.
Fall armyworms can be expected through September, both in hay meadows and lawns.
“Remember, armyworm outbreaks often occur in waves about 30 days apart, indicating the need for routine scouting,” Loftin said.
For more information about pests visit www.aragriculture.org/News/pestmgmt/2011/july252011.pdf, or contact your county Extension office.