In the laboratory, fipronil was tested against laboratory-reared and field-collected early 4th-instars of Aedes albopictus. The insecticide was also bioassayed for activity against natural field populations of Ae. albopictus inhabiting 1-liter–capacity stone-made containers in a cemetery in St. Augustine, FL. The cemetery containers also were utilized to study initial efficacy and activity persistence of fipronil against natural populations of Ae. albopictus. The laboratory-reared larvae were 2-fold more susceptible than field-collected larvae as indicated by the 50% lethal concentration (LC₅₀) values of 2.6 and 6 parts per billion (ppb) for laboratory-reared and field-collected larvae, respectively. In the field bioassay, in stone-made containers, the LC₅₀ value of Ae. albopictus larvae amounted to 57.5 ppb. In the cemetery containers, fipronil applied at 3.2 and 32 ppb gave 100% control of Ae. albopictus larvae with either rate of application for at least up to 8 wk posttreatment.