The Deep South's nastiest soybean pest is marching north, and Mississippi and Arkansas are facing their worst invasion ever.
Two warm winters followed by this year's warm spring have let invasive red-banded stinkbugs spread well beyond south Louisiana, where they've been prevalent since 2000.
It's much worse than 2009, the last time the insects were a big problem in Mississippi and Arkansas, experts say.
"There are huge numbers," said Gus Lorenz, an entomologist with the University of Arkansas extension service in Lonoke.
For instance, he said, "there were so many they had to quit harvesting" Aug. 20 in Lake Village. So many bugs were getting into the combine that grain elevators would have rejected the loads as contaminated with foreign matter, he said.
"We're finding it close to the Tennessee line," though in smaller numbers that far north than in central and south Mississippi, said Angus Catchot, an entomologist with the Mississippi State University extension service in Starkville.
Jeff Davis, an associate professor of entomology at the Louisiana State University AgCenter , said the 2009 infestation didn't continue into 2010 because a cold winter and spring killed many of the bugs, which are neotropical critters from South America.
"The only place it survived was in southern parishes of Louisiana. Since then, they've been marching their way north," he said.
And many survived the past two winters, munching on clover.
"It's a really good year ... for stink bugs," Davis said. "It's a bad year for a soybean grower."
Arkansas is the mid-South's biggest producer, with 3.5 million acres of the beans. Mississippi has more than 2 million acres, Louisiana 1.3 million. Texas plants about 200,000 acres a year, according to the U.S. Department of Agriculture's National Agricultural Statistics Service. Farmers are finding normal to above-normal numbers of red-banded stink bugs west of Houston, but nothing like the infestations in Arkansas and Mississippi, said Mo Way, of the Texas A&M AgriLIFE Resarch Center at Beaumont.
Red-banded stink bugs are smaller but can do more damage than their native cousins.
"Their piercing, sucking mouthparts can go farther, deeper into seeds and into the pod wall," said Davis. They can also expand them into wider tubes than the local brown, green and southern green stink bugs do, slurping up more at a time. And they seem to have more aggressive enzymes in their saliva, too.
Lorenz said the critter also out-reproduces native stink bugs.
Experts recommend applying pesticide if 25 sweeps with a heavy canvas net bring up four red-banded stink bugs, compared to nine for the indigenous stink bugs.
"From Pine Bluff south, it's not uncommon to see two per sweep. ... That'd be approximately 10 to 12 times the threshold," Lorenz said.
Alabama farmers also are being warned to keep an eye out. "They love late-planted soybeans or soybeans planted behind wheat," Auburn University extension entomologist Ron Smith said in an Aug. 14 news release.
Red-banded stink bugs are not a threat yet in Georgia, said Philip Roberts, at the University of Georgia extension service .
Arkansas and Mississippi extension agents were getting so many calls that they met with Louisiana's experts for an emergency forum Aug. 17 in Stoneville, Mississippi, to tell farmers and consultants how to deal with the bugs.