Rice delphacid presents new threat to MS crop

STARKVILLE, Miss. -- Rice delphacid is a plant hopper that has been damaging Texas rice since 2015, and this invasive threat to Southern rice production made its appearance in Mississippi last year.

Rice delphacid is native to Central and South America and has been slowly moving north. In addition to Mississippi, it was found in Louisiana and Arkansas in 2025.

Don Cook and Tyler Towles, entomologists with the Mississippi Agricultural and Forestry Experiment Station, found this pest in mid-September in Mississippi State University rice fields at the Delta Research and Extension Center in Stoneville.

After its discovery in Washington County, it was also observed in Bolivar, Humphreys, Leflore and Sunflower counties, which are some of the state’s primary rice-producing areas.

“Rice delphacids feed on various grasses, with rice being its primary and most economically significant host,” Cook said. “They show up in very high numbers, and in addition to the leaf damage that causes yield loss, they excrete excess sugar as honeydew, and this leads to sooty mold in the rice.

“They also carry a virus that causes Rice Hoja Blanca disease, which can cause the rice grains not to develop, resulting in an empty or blank head,” he said.

Rice delphacids are small piercing and sucking insects -- typically about a quarter inch long – that feed on the juices in rice plants.

“Males are brown with black patches at the tips of their wings, while females are paler in color. They are winged and have a light-colored stripe down their backs.

Management of rice delphacid has been an issue in Texas. The pest causes varying degrees of problems there each year, with 2025 being the worst year for problems with this pest.

“We potentially had minimal yield losses in 2025 in Mississippi from the rice delphacid that moved into our area,” Cook said. “For most fields, the losses were limited because the pest arrived very late in the growing season. The impact of infestation timing depends on when rice gets planted.

“With our typical planting schedule, most of the rice would not be susceptible to infestations if infestations occur in mid-September or later,” he said. “If infestations occur earlier, then more of the rice crop could be impacted.”

Insecticides labeled for use in rice have had very limited control of this pest. Cook said the hope is that winter weather will contain the spread of this pest and make it difficult for delphacid to overwinter in the Mississippi rice-growing areas.

Nick Bateman, an entomologist with the University of Arkansas, brought the insect pest to the attention of participants of the MSU Row Crops Short Course in January.

“This pest cannot survive direct exposure to cold, but leaf litter can provide a lot of cold protection,” Bateman said. “We found that 24 hours at 20 degrees kills 100% of the population, but 24 hours at 21.2 degrees kills just 93% of the population.”

He also reported that 100% of eggs are killed when exposed to 43-degree temperatures for 24 hours.

Cook said MSU is part of a task force that also includes researchers from Texas, Arkansas and Louisiana.

“Results of insecticide trials on this insect show that a tank mix of Transform or Tenchu -- both labeled for use in rice -- plus Courier, which is currently not labeled for rice, provided the best control.

Cook said Texas, Louisiana, Arkansas and Mississippi are in the process of submitting a Section 18 Emergency Use Request for Courier, but there is no guarantee that the EPA will grant this. And if granted, Cook said its use would be expensive for growers.

Will Eubank, rice specialist with the MSU Extension Service, said specialists are hoping that this pest cannot survive Mississippi winters. If it cannot overwinter locally, it would have to move north into the state from warmer areas each year.

“Its arrival in 2025 was too late for the pest to make an impact in most areas,” Eubank said. “This pest likes to feed during the heading stages when it can really impact growth and yield.”

A late arrival each year may prevent them from causing significant economic losses.

Rice delphacids reproduce rapidly, and their numbers can get very high quickly.

“I visited one field in October where, from the turnrow, I could see discolored splotches in the field,” Eubank said. “I went out to that area and swept one plant and easily got 1,000 plant hoppers.”

The pest is most dangerous at its nymph stage where the high number of insects can literally suck the life out of a plant. But as long as the pest continues to arrive in late August or September, most of Mississippi’s rice crop should have already set heads and be largely immune to significant yield losses.

Keep up with the latest crop news and management advice from MSU experts by visiting the Mississippi Crop Situation at https://www.mississippi-crops.com.