By Heath Grigg, Texas & Southwestern Cattle Raisers Association director and chair of the cattle health & well-being committee
Since spring 2025, Texas ranchers, landowners and hay producers have watched isolated patches of dying forage spread across pasture and hay fields,
leading to widespread forage loss and, in severe cases, the destruction of entire fields.
Early reports presumed these observations were caused by the Rhodesgrass mealybug, a pest already known in Texas. Subsequent investigations confirmed the damage was instead caused by the pasture mealybug.
The pasture mealybug is an introduced pest and a newly recorded species in the U.S. Although it was only recently identified in North America, researchers suspect it may have been present before 2022. The insect was first documented in Australia in 1928. Its first confirmed detection in the Western Hemisphere occurred in the Caribbean between 2019 and 2020.
Adult female pasture mealybugs are tiny, measuring just 2 to 5 millimeters long. The white, oval-shaped insects are covered in a waxy coating that gives them a fuzzy appearance. They can thrive on nearly all warm season grass species.
At time of press, the pasture mealybug has been confirmed in 79 Texas counties, affecting grasslands from the upper Rio Grande Valley east to the Louisiana- Texas border.
Until recently, no pesticides were labeled to effectively control pasture mealybugs; therefore, planning for and investing in protections for pasture and rangelands is overdue.
Texas AgriLife researchers estimate pasture mealybug threatens more than 20 million acres. If the pest is established in the 56 counties currently considered at imminent risk, that figure could climb to nearly 36 million acres. Funding for the research and containment efforts to eradicate this devastating pest is critical. Otherwise, ranchers and landowners are at risk of pasture loss — and resulting economic hardship.
Texas AgriLife Extension submitted an emergency insecticide use exemption with the EPA for pesticides demonstrating effectiveness in test trials. The Sefina insecticide has shown some ability to suppress low populations in pastures, according to researchers.
On Aug. 11, Centric 40WG received EPA approval through a Federal Insecticide, Fungicide and Rodenticide Act Section 18 Crisis Emergency Exemption. While this exemption isn’t permanent, there is presently a labeled option that research shows will work if applied correctly. Efficacy of Centric is limited though, with control periods estimated to be 21-28 days, allowing populations to rebuild and requiring more than one insecticide application.
Ranchers and landowners are encouraged to regularly inspect fields and look for grass that is yellowing, slightly reddening and growing poorly, especially after rainfall. Symptoms are often mistaken for nutrient deficiency. Pasture mealybugs thrive in tall, dense forage, so reducing biomass through cutting, shredding or heavy grazing will reduce mealybug populations.
Efforts by state and federal agencies are crucial as solutions are identified for a pest that poses an imminent threat to U.S. pastures and forage.
As land and natural resource managers, we must be diligent in protecting the health and longevity of the grasslands in our care. This means reacting appropriately to threats — and being proactive toward reporting and mitigation.
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