Texas A&M researchers discover new invasive pest affecting pastures and livestock

There's a new invasive pest that could damage millions of acres of Texas farmland and financially hurt livestock producers: the pasture mealybug.

First discovered in 2025, the small pest feeds on plant sap and injects toxins that weaken plants, often resulting in a condition known as pasture dieback. The bug has been found to mostly feed on various types of grass in Texas, which Texas A&M experts say could effect the state's $15.5 billion cattle industry by threatening its hayfields and grazing livestock.

"It's hard to to determine the economic impact (of these pests)," said David Kern, a professor and extension entomologist at Texas A&M University. "But we're thinking, potentially millions of acres could be affected, and we're thinking that just the economic impact could be in the billions (of dollars)."

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The majority of damage to grass occurs when the mealybug's nymphs feed on the plants, Kerns said.

The invasive pest has been found in 70 counties, with those in south and central Texas most heavily infested. Kerns said counties of Southeast Texas, such as Colorado, Jackson, Liberty and Wharton, were fairly infested.

He said the spread of pasture mealybugs across the state was "extremely fast," and it's possible that the pest already lived in many areas before researchers discovered them. 

"They're so small, the nymphs are so small that you really can't see them without magnification, and they hide," Kerns said. "It's not something that's easy to detect unless you're really looking for them."

Pasture mealybugs have oval-like bodies, a waxy white coat and are about 2- to 5-millimeters-long.

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The new invasive pest comes as state officials are sounding the alarm about an outbreak of the New World screwworm, which was discovered early June in Zavala County in South Texas. The fly is potentially fatal to cattle. 

Kerns said the discovery of both invasive pests is "a double whammy" to ranchers as they are timely and costly burdens.

"If in these areas where they've picked up screwworms, the ranchers have the the burden of of having to certify their cattle as being screwworm-free before they can move them," Kerns said. "And of course, trying to manage this mealybug in in the pastures and rangelands is also an added expense."

Kerns said there's only been one labeled insecticide that has shown zto have some effect on controlling pasture mealybug infestations: Sefina. However, the pesticide only offers to suppress mealybug populations in pastures and not eliminate them.

He said though that test trials have shown some success with other pesticides, and he is currently attempting to work with the Environmental Protection Agency and the state's agriculture department to get an emergency insecticide use exemption to use pesticides.

"The the impact (of mealybugs) could be substantial, but I think it's a manageable pest," Kerns said. "If we get the right tools and and use them properly, because there's some cultural things we can do with the right insecticide tools to manage the pest."

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