Forage Growers May Need To Be On Alert For Bermudagrass Stem Maggot
DR. RAUL T. VILLANUEVA
LEXINGTON, KENTUCKY
The bermudagrass stem maggot (BSM), Atherigona reversura (Diptera: Muscidae), is native to Southeast Asia and was first reported in the continental United States in 2009 in California. In 2010, it was detected in southern Georgia and has since spread throughout the southeastern U.S., infesting bermudagrass hayfields, pastures, and turf. By 2013, BSM was found in Kentucky by Dr. Townsend. The pest has now been reported as far north as Ontario and is present across much of the southern United States.
The larval stage of BSM bores into the upper portion of bermudagrass tillers, often killing the shoots (Figure 1). Field damage varies depending on the grass growth stage and the density of fly populations. Injury tends to increase during the summer, especially under drought stress conditions.
Current Status & Management
An infestation of this pest was reported in Pulaski County. Given the current lack of rainfall in August 2025, new reports may emerge soon.
Cultural control is possible if the harvest is done on time and the field is in good condition: adequate fertilization, effective weed control, and a healthy plant stand. As this is an invasive species, natural parasitoids are not known. While predatory insects or spiders may feed on the flies, they are not effective in suppressing populations of BSM.
Chemical suppression of the maggot or larval stage would require a systemic insecticide, which is costly and not recommended. Dr. Baxter from the University of Georgia has the following recommendation:
“Populations of the BSM fly can be suppressed by applying the recommended rate of a pyrethroid insecticide at 7 to 10 days after harvest and a second application 7 to 10 days after the first application. The first application helps control adult flies that recently emerged from the soil or moved into the field from neighboring areas. The second application controls flies that have emerged from eggs laid before the first application or pupae that had not yet emerged. Pyrethroid insecticides are the only effective mode of action available on the market today. Malathion, carbaryl, chlorantraniliprole, and spinosad are not effective at controlling the BSM”.
More Information
- Early Frost or the Bermudagrass Stem Maggot? (UK Kentucky Pest News)
- Baxter, Lisa L., et al. 2024. Improved management of the bermudagrass stem maggot. Crop, Forage & Turfgrass Management 10.1 (2024): e20269. ∆
DR. RAUL T. VILLANUEVA
UNIVERSITY OF KENTUCKY