Pasture Mealybug Update--June 19, 2026

By Dr. Blake Wilson

LSU AgCenter

The pasture mealybug, Heliococcus summervillei, has been confirmed to be infesting sugarcane in Vermilion, Iberia, and West Baton Rouge Parishes. The pest is a recently detected invasive insect in the U.S. that is native to India, southeast Asia, and Australia. In its native range, pasture mealybug is a major pest of pasture grasses, but has also been recorded from sugarcane, rice, and numerous other grass species. Pasture mealybug has been causing dieback of pasture grasses in Texas since at least 2025. It was also recorded infesting both pasture and sugarcane in south Florida in 2026. In Louisiana, infestations have been observed in many sugarcane fields in Iberia and Vermillion Parishes, particularly along the Highway 14 corridor from Kaplan to New Iberia.

The West Baton Rouge detection occurred near the Mississippi River in Port Allen. No detections of pasture mealybug have been made in pasture grasses in Louisiana yet, but infestations are anticipated. Distribution of the pasture mealybug is being actively monitored, and suspected infestations should be reported to the LSU AgCenter (bwilson@agcenter.lsu.edu) and the Louisiana Department of Agriculture and Forestry (PastureMealybug@ldaf.state.la.us). Care should be taken to avoid spreading pasture mealybug when moving from infested fields to uninfested fields. No quarantines are currently in place, but movement of infested plant material is strongly discouraged. Equipment used in infested fields should be thoroughly washed with high pressure hoses. A bleach solution may improve cleaning. No insecticides are registered for application to farm equipment and their use is not recommended. Infested sugarcane fields frequently have yellowing leaves in the middle to lower canopy. Pasture mealybug nymphs range in size from very small (<0.5 mm) to small (≈3 mm) and are covered in webbing or fuzz-like hairs (Figure 1). A magnifying glass or hand lens can help to see the smaller nymphs.

They are mobile and often can be seen moving around on the underside of sugarcane leaves in the mid-canopy. All Louisiana varieties are thought to be susceptible. Impacts to sugarcane are still being evaluated. Yield loss resulting from infestations cannot be accurately measured until harvest. The small number of infested fields in 2025 had reduced tonnage and very low sucrose recovery. Ongoing research is investigating efficacy of insecticides. A Section 18 Quarantine Exemption has been obtained for the use of Sivanto Prime on sugarcane in Acadia, Assumption, Cameron, Iberia, Iberville, Jefferson Davis, Lafayette, St. Martin, St. Mary, and Vermillion Parishes (approximately 267,000 acres). That label will remain valid for the 2026, 2027, and 2028 growing seasons.

A request has been submitted to expand that label to allow for statewide usage. Sivanto Prime applied at 7–14 fl oz/acres has provided effective control in fields that have been treated in 2026. When treating, producers are encouraged to leave a portion of fields unsprayed so infestations can be monitored and yield loss measured. Thresholds to guide application decisions have not yet been developed. Pyrethroids registered for use in sugarcane are not recommended at this time and have been reported to increase infestations in Texas pastures. Contact Blake Wilson (bwilson@agcenter.lsu.edu, 985-373-6193) for further information.