Mosquitoes Get In But They Can't Get Out

About the Program

Category: Health (Best in Category)

Year: 2017

York County, Virginia uses both gravity and vacuum sewer systems. According to a two-year project done by York County Mosquito Control staff, vacuum pits, which are part of the vacuum sewer system, have shown to be a significant mosquito breeding source. These pits had not previously been treated for mosquitoes in York County or its neighboring localities. For the approximate 1,600 vacuum pits in York County, staffing levels and costs necessitated that the larvicide used in the pits provide season-long control (up to 25 weeks) with a single treatment. Forty vacuum pits in the Dare area of the county were selected for observation. Twenty pits were treated with one Natular XRT tablet each, while the other 20 were left untreated. Treatments were applied in May 2015 and May 2016; and the pits were sampled for larvae biweekly for 180 days. Throughout the project, the treated pits had significantly fewer larvae than the untreated pits. The study led to implementation of a larvicide program for the vacuum pits in York County. Vacuum sewer systems are used in many states, particularly in low-elevation areas that are prone to flooding. Due to these systems being cost-effective, having a lower environmental impact than some systems, and being energy-efficient (compared to traditional gravity systems), vacuum systems are likely to become increasingly used throughout the country. Because of this, we recommend treating vacuum pits with extended-use larvicide, for effective control of mosquito larvae for up to 180 days per treatment.