If weather conditions are favorable for effective spraying, the City of Sioux Falls Health Department will be conducting ultra low volume ground spraying efforts for mosquitoes in targeted areas of Sioux Falls this evening.

A map on the City’s Website outlines the targeted zones where spraying will occur. Sioux Falls Zone(s) 7, 10, 11, 12, 13, 15, and the rest of 14 are scheduled for spraying tonight due to increased numbers in Culex tarsalis (the encephalitis mosquito) and Aedes vexan (nuisance mosquito) populations. The Sioux Falls Phased Response Guidelines indicate specific response parameters when numbers of Culex and Aedes species hit set threshold limits. Therefore, the Sioux Falls Mosquito Control Program is conducting comprehensive treatments including increased education, surveillance, and control measures in accordance with CDC and local phased response guidelines.

This evening’s spray will begin as early as conditions are favorable; possibly as early as 8 p.m. and will continue until 1 a.m., or until the designated areas are completed. Once spraying commences, changing weather conditions may prevent the completion of some areas; these will be completed as soon as weather permits.

The Sioux Falls Mosquito Control Program is working hard to control mosquito numbers but that doesn’t mean people can stop protecting themselves. New research from South Dakota State University is indicating that as much as 50 percent of Culex activity occurs in the two-hour period between 10 p.m. and 12 midnight. That information helps control programs better target their mosquito fogging efforts but also serves to reinforce the need to use repellents throughout the evening hours.

“The most aggressive mosquito control program in the world cannot eliminate every single mosquito. That’s why it’s so important that people protect themselves by using repellent and staying inside during when the mosquitoes are most active,” said Denise VanRoekel, the City’s Vector Control Coordinator. “That’s especially true now that West Nile cases are increasing.”

The following precautions should be followed to prevent mosquito bites and reduce the risk of West Nile Virus: 

• Use mosquito repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus. 
• Wear shoes, socks, long pants, and a long sleeved shirt to limit exposure to mosquitoes. 
• Limit time outdoors at dusk and dawn when mosquitoes are most active. 
• Eliminate standing water that gives mosquitoes a place to breed. 
• Support local mosquito control efforts.

The elderly, pregnant women, diabetics, transplant patients, individuals with high blood pressure, and those with a history of alcohol abuse should be especially mindful to take precautions. People with a severe or unusual headache should see their physician.

The City will be using the products Aqua-Reslin® and Scourge (resmethrin) in the city limits and in the counties. Scourge is a synthetic pyrethroid approved for use by the EPA in residential areas for adult mosquito control and Aqua Reslin® is a Permethrin based product using a water carrier. The products used by the Sioux Falls Mosquito Control Program inside the city limits as well as in the county are designed to break down in the environment quickly and at the very low concentrations used, are unlikely to cause adverse health effects in humans or mammals.

In order to be effective, all sprays for adult mosquitoes must be conducted in the evening or very early morning hours when the mosquito that transmits West Nile Virus is most active, and during favorable conditions of weather. Exact dates for future sprays cannot be given and the exact time when spray trucks will be in a specific area is not known. Residents are not required to relocate, stop activities, or take special precautions during mosquito control spraying. For safety reasons, residents should never deliberately approach or follow spray vehicles.

People who want to avoid all exposure to the chemicals can take the precautions indicated on the City’s Website. An audible tone and visible signal will precede the marked spray truck. If residents have concerns or questions, they may check the City’s Website, cable channel CityLink 16, or call the Health Department for more information. Additional information on synthetic pyrethroids can be found at http://www.epa.gov/oppsrrd1/reevaluation/pyrethroids-pyrethrins.html.

Citizens do not need to call the Health Department to report areas of standing water a second time. All areas of town are being surveyed and previously treated areas will be rechecked. Citywide sprays cannot control private properties with large amounts of vegetation or standing water that harbor or support excessive numbers of mosquitoes locally; and therefore, these may require additional local control by the homeowner or business.

As progress is made toward completing the spraying process, updates will be placed on the City’s Website. In order to view the spray map or for additional information, visit the website at www.siouxfalls.org. Citizens wanting to report local concerns on biting or standing water should leave the required information on the automated Mosquito Reporting Hotline at 605-367-8799.