Grasshopper infestation gives cause for concern
- Mardi Ford
Cory Parson's assessment of the grasshopper infestation plaguing the region is expressed with a long, drawn out groan. Finally, he speaks. "When it rains, it pours."
The livestock Extension agent for both Baker and Union counties says the ranchers and farmers who have contacted him about the infestation are already being hit hard by drought. The double hammer of a hay shortage and resulting higher hay prices now has the added weight of grasshoppers.
"Whatever hay the drought didn't get, grasshoppers are," Parsons says. Typically, grasshoppers stay in the rangelands, but between wildfire devastation and drought, rangeland forage is scarce in many areas.
Since grasshoppers live to do two things Â— eat and make more grasshoppers Â— they find food where they can.
"They're chasing the green. Out on the range land and sage brush, nobody sees them. In a drought like this, they move in and start mowing down the alfalfa field. Some folks are saying even though they keep watering their lawns, they haven't had to mow them in a month. They're eating people's gardens. And in some places over here," Parsons said from his office in Baker County, "we're seeing them eat the leaves off peach and apple trees clear down to the limb. They're even stripping pine needles off fir trees Â— those trees won't come back next year. "
Although Extension forester Paul Oester has not seen any deforestation from grasshoppers in Union County, he says large evergreen trees would most likely survive having some of their needles eaten.
"But with a high infestation, it's the smaller four- and five-foot evergreens that would be susceptible. In a severe infestation, even the bark and bud are eaten," he says.
Though the scope of this year's infestation may be the worst many have seen in a long time, it is sporadic. The grasshoppers are thick in Sparta and Haines. Other farmers and ranchers outside of Baker City say they aren't seeing any more than usual, Parsons says, but Medical Springs and North Powder are now infested.
The Cricket Flat area north of Elgin is also registering large numbers. Union County Extension agent Darrin Walenta said grasshoppers were "pretty thick" northeast of Wallowa when he was there last week.
"The bad thing about grasshoppers is that they're mobile," said Parsons.
Entomologist Helmuth Rogg is the Oregon Department of Agriculture's expert on insects in Eastern Oregon. He has been studying the infestation already occurring in Malheur and Klamath counties.
Last week, he spotted the clearwinged grasshopper at Morgan Lake.
"I haven't seen that species here before," Rogg says.
This year, the grasshopper infestation is spreading across more than 270,000 acres in both Union and Baker counties, with as many as 75 grasshoppers per square yard in the worst places. What might be considered normal during a seasonal grasshopper outbreak would be 12 to 14 grasshoppers per square yard.
While talking to a Sparta rancher about the huge infestation, Rogg said he could actually hear the grasshoppers eating the grass. The numbers he is seeing here this year, he says, "are a huge concern."
"It could be these numbers have been seen before, but I can't say," he says. "This is my third summer here, so I don't have a long history to go back on. It could be we are entering a new cycle in this area."
As with most things in nature, Rogg says insect hatches and outbreaks can be cyclical. Weather also plays an important role. Rogg says cold winters will not kill the eggs hibernating one to two inches below the soil surface. And a warm, dry springs will favor the hatch of nymphs.
It is the vulnerable nymphs that are the voracious eaters causing the greatest damage. They must consume huge amounts of food to grow into mature grasshoppers, ready to mate and fly. Rogg says once they reach adulthood, they don't eat as much.
But it is at the mature stage when people notice grasshoppers, as they move in swarms eating, mating and seeking light, sandy soil conditions to lay their eggs. Female grasshoppers will lay as many as 800 eggs scattered in several eggpods containing as many as 40 individual eggs. In a typical outbreak situation, he says, up to 100,000 eggs may be found in one square foot.
Rogg says once they reach the adult stage, it may not be economically viable to use pesticides as the crop damage is done, the grasshoppers have mated, already laid their eggs and are dying anyway.
Rogg says pesticide control works best during the nymphal stage. The ODA's preferred choice of chemical is Dimilin (diflubenzuron), a growth hormone inhibitor.
Rogg says Dimilin interferes with the hormonal system of the insect's molting process. The nymph dies in its old skin when it is trying to molt. Dimilin is relatively specific, he says, and does not affect adult insects like bees or other pollinators.
Although rangeland in the Grande Ronde Valley is more limited and crops on the valley floor have escaped infestation, in a severe outbreak with limited food sources grasshoppers can affect wheat fields.
In cooperation with the OSU Extension Services in Baker and Union counties, and the USDA, Rogg is putting together an informational meeting for area ranchers and farmers this fall to outline the current situation and what he expects could happen next year Â— especially if there is a warm winter followed by a warm, dry spring.
"There is some federal cost-share money available for spraying, but we need to organize to apply for it. It is up to the ranchers and farmers what they want to do, but I want them to have all the information they need to make that decision," Rogg says.