Thursday, August 30, 2012

Current Assessment of Florida’s Mosquito Populations and Danger to Floridians

Current Assessment of Florida's Mosquito Populations and Danger to Floridians

The major rain events from Tropical Storm Debby and recently from Tropical Storm Isaac have created conditions that are perfect for "floodwater" mosquitoes in Florida.  Floodwater mosquitoes are those whose eggs remain in the soil for months or even years, and then hatch during flooding events.  The adult population can then be horrendous, prompting calls to mosquito control agencies and complaints to local government.  The mosquito populations from the most recent tropical storm will be noticeable for a few weeks.  One important detail to remind people about is that floodwater mosquitoes are generally not involved in transmission of West Nile virus.  For a fact sheet that explains floodwater mosquito behavior, see:  

The U. S. is currently experiencing the worst West Nile outbreak since it was first detected in the U. S. in 1999.  This outbreak is currently worst in Texas.  Thankfully Florida has so far been spared from such an extensive epidemic but we still need to remind Floridians about this disease, and that the primary floodwater mosquitoes are not vectors of West Nile virus.  The immediate threat to Floridians will be the prodigious numbers of pest mosquitoes resulting from Issac's rainfall that will make outdoor life in Florida far less enjoyable over the next few weeks.

The Florida Medical Entomology Laboratory (FMEL – UF/IFAS) has released their fourth FMEL Arboviral Epidemic Risk Assessment for 2012.  The risk assessment provides the current outlook for West Nile virus (WNV), St. Louis encephalitis virus (SLEV), and Eastern equine encephalitis virus (EEEV) transmission in Florida based on the current Arboviral Epidemic Risk Models (AERMs).  The AERMs are based on Modeled Water Table Depth (MWTD) in Peninsular Florida for SLEV and WNV, and Keetch-Byram Drought Index (KBDI) data for EEEV throughout the entire state coupled with knowledge about the biology of the major West Nile mosquito vectors and bird host populations.  This assessment is current through August 14, 2012 (Week 23) and further updates will be issued as needed throughout the arboviral transmission season.  The latest update can be downloaded as a PDF file at  General information about the AERMs and archived updates can be found at

Your State of Florida and local County Health Department provides advisories and alerts related to mosquito-borne illness.  Always encourage the public to pay attention to all mosquito-borne illness advisories and that it is always prudent in Florida to wear repellents when they are outdoors but particularly so when there are advisories of increased risk.  You can view Arbovirus Surveillance updates from the Florida Department of Health at:

Mosquito-borne Disease Maps for 2012 and previous years for West Nile Virus, St. Louis encephalitis, Eastern Equine Encephalitis, and Dengue, are provided by the USGS and CDC.  From the U.S. map, you can click on the State of Florida for details by county for humans, birds, mosquitoes, sentinels, and veterinary (horses):

Remember that IFAS Extension has several fact sheets on mosquitoes and mosquito-borne diseases that will provide useful information to the public: 

Dengue:; Spanish version at:

Eastern Equine Encephalitis: ; Spanish version at:

Mosquito Repellents: ; Spanish Version at:

St. Louis Encephalitis:

West Nile:; Spanish version at:

For more information on the mosquito-borne encephalitis viruses of concern in Florida, visit the FMEL's Encephalitis Information System at  This can be viewed in English or Spanish.



C. Roxanne Connelly, PhD

Associate Professor

Extension Specialist, Medical Entomology

Past President, Florida Mosquito Control Association

President-Elect, American Mosquito Control Association



200 9th Street SE

Vero Beach, FL  32962


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