About the Pilot Study

What is a 4-Poster Deer Treatment Station?

A ‘4-Poster’ deer treatment station is a feed station that uses corn to bait deer and treat the deer with a pesticide to kill ticks.  A total of 4 posts, that resemble paint rollers, are placed on the corners of the station next to two shallow feeding troughs located on both sides of the station. The posts are saturated with a pesticide (10% permethrin) used to kill ticks on the deer. A deer rubs its head and neck against the rollers as it lowers its head to the trough to feed on the corn at the station. This direct contact results in a self-application of the pesticide on the deer. The pesticide is further spread on the deer’s body during regular grooming activity. 

The ‘4-Poster’ technology was first developed in 1996 by the United States Department of Agriculture to control tick infestations on cattle.  The device and specially formulated pesticide was registered with the U.S.Environmental Protection Agency for commercial use in 2004 following several years of extensive research.  Gibson Island, Maryland became the first locality to commercially use these deer treatment stations, in 2005.

Background Information

The Fairfax County ‘4-Poster’ pilot study is a novel research project to control tick infestations on white-tailed deer (Odocoileus virginianus) at test sites in Fairfax County, Virginia using 4-poster deer treatment station technology.

Deer are the primary host of adult blacklegged ticks (Ixodes scapularis) which can transmit Borrelia burgdorferi, the bacteria that causes Lyme disease. Deer are also primary hosts for the Lone Star tick (Amblyomma americanum). More information about tick-transmitted diseases, disease prevention, and tick identification is available from the Fairfax County Health Department’s Disease Carrying Insects Program.

The Fairfax County "4-Poster" pilot study is a tick control study only, not a tick transmitted disease control or prevention study.

Credit: Peter Priolo

Virginia does not currently permit legal commercial use of 4-poster deer treatment stations.  The Fairfax County pilot study is being conducted under a scientific collections permit issued by the Virginia Department of Game and Inland Fisheries. The research is an extension of the Fairfax County Deer Management Program implemented each year by the Fairfax County Wildlife Biologist Office.

Development of the pilot study has been underway since August 2009, with full support by the Board of Supervisors. The pilot study is being funded by the Health Department through Fund 116, Integrated Pest Management. The three-year study is anticipated to cost approximately $380,000, including personnel costs and operating expenses associated with purchase and maintenance of the treatment stations.

Research Goals

Over the course of the three-year pilot study, considerable biological data will be collected and analyzed in an effort to assess:

  • Efficacy of the devices in reducing the density of ticks carried by free-roaming wild deer at each test site, and comparing tick densities between test sites and the control sites.

  • Practicality of the devices as a method for reducing the density of ticks carried by deer.

  • Effect of year-round corn baiting on the overall herd health of free roaming wild deer.

Deer Treatment Station Locations

Full deployment of the deer treatment stations is expected from March 2012 through February 2015. Twenty stations (20) have been deployed at two test sites on public parkland: Hemlock Overlook Regional Park, a Northern Virginia Regional Park Authority park, and Sully Woodlands, an assemblage of several Fairfax County Park Authority park properties.

Fences have been constructed around all twenty treatment stations. Signs have been clearly posted at each fence plot site and park patrons are prohibited from handling any equipment or entering the fence plots. Each station is under police surveillance.

Two control sites have been selected on Fairfax County Park Authority property to collect tick data and other biological data: Laurel Hill Park and Braddock Park.  Data collection is ongoing at both sites for the duration of the three-year study.  No deer treatment stations are deployed at either control site.



Marking Treated Deer

Pink dye will be added to the rollers at each station to mark and identify deer that are treated with pesticide as they come to feed.  The non-toxic dye will leave a bright pink mark on all treated animals and will fade in 3 - 4 days.  It is possible that other animals may be attracted to the bait used at the deer treatment stations.

 Residents should not be alarmed if they notice wildlife, other than deer, that may come into contact with the pink dye at the treatment stations. Any animal large enough to rub against the roller posts may be marked by the pink dye. Raccoons, squirrels, turkeys, fox, and crows have been viewed using these stations to feed on corn.


It is requested that residents report sightings of any deer, or other wildlife, marked with pink dye while the pilot study is in progress.

Contact Fairfax County: Phone, Email or Twitter | Main Address: 12000 Government Center Parkway, Fairfax, VA 22035
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