Floodwater water mosquitoes (Aedes vexans) are practically nonexistent due to prior control efforts and lack of any significant precipitation throughout most of the District. Most of our control efforts continue to be directed at Culex stagnant water mosquitoes. Catch basins, detention/retention & building foundation (Villages are encouraged to report new building constructions to NWMAD) treatments are the predominant production areas. The District is starting its third round of catch basin treatment with the insect growth regulator methoprene. Other stagnant water sites will be treated with the microbial insecticide Bacillus sphaericus.

Homeowners are strongly urged to remove any stagnating water on their property that may produce these mosquitoes. Culex mosquito numbers start to increase this time of the season even under drought conditions. Virtually any water container (i.e. flower pots, garbage cans, pails, bird baths, un-maintained swimming pools, etc) containing organic debris like leaves or grass can produce hundreds of these mosquitoes in about a week’s time during warm temperatures. Homeowners should also avoid watering lawns near open ditches or low areas that may cause water to accumulate in culverts under roadways.

ADULT MOSQUITO SPRAYING

Because West Nile virus (WNV) has been found in birds and mosquitoes in our District and Culex mosquito numbers are on the rise it is likely that we will engage our night spraying program the remainder of this week weather permitting. Targeted areas would be Northbrook where increasing WNV positive mosquito pools have been found and Wheeling, Hanover, Elk Grove & Maine townships with of high Culex mosquito trap counts.

Culex mosquitoes primarily feed on the blood of birds and don’t normally prefer humans. When numbers of these mosquitoes increase as they typically do into the summer the chances that they may take a human blood meal also increases. Our Night Spraying Program helps reduce adult Culex numbers and it is the only practical method of controlling adult mosquitoes already infected with WNV and capable of transmitting the virus to more birds (amplification) or possibly humans.

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested 190 Culex mosquito pools to date for West Nile Virus and St. Louis encephalitis. Seven mosquito pools have tested positive for WNV via the VecTest. Six pools were from Northbrook and one from Wheeling. Mosquito pools testing positive in the District will be posted in this Newsletter as well as the NWMAD website www.nwmadil.com.

DEAD BIRD SURVIELLANCE INFORMATION:

As of this writing 98 birds have tested positive for WNV in Illinois according to the Illinois Department of Public Health. Birds were collected from 31 counties in Illinois. Current information about WNV can be found on the state’s website www.idph.state.il.us/envhealth/wnv.htm or by calling 217-782-5830.

WEST NILE VIRUS AND THE ELDERLY

Although the risk of being bitten by a WNV infected mosquito is considered small and most people that are infected show few to no symptoms of the virus it’s important to remember that those most likely to be susceptible to the virus are people over 50 years old and individuals with compromised immune systems. The reason for the susceptibility in this age group is not entirely understood but thought to be due to decreasing immunity as a person ages. Some suggestive evidence to support this theory is that children appear to be less sensitive to WNV because of immunity passed on to them by their mothers. It is therefore very important that the elderly be warned to avoid mosquito bites during peak mosquito activity (esp. around and between dusk and dawn).

REDUCING THE RISK OF MOSQUITO BITES:

Avoid outdoor activity if possible from dusk to dawn when the mosquitoes bite the most. If you do go out wear light colored, loose fitting, protective clothing and insect repellent (always read label warnings and directions). Make sure mosquitoes do not enter homes through unscreened or broken doors or windows. Residents are encouraged not to create mosquito harborage areas. Make sure tall grassy areas are trimmed and other unnecessary vegetation is cut back. If plants must be watered do so in the morning so the vegetation and soil has a chance to dry making it less attractive to mosquitoes. Empty any containers holding stagnating water for 5 days or longer like: tire casings, bird baths, flower pots and barrels that may produce mosquitoes. Neglected swimming pools may produce thousands of mosquitoes. Call the District to report large stagnant water areas that remain wet for more than 7 days.

Mike Szyska

Director

Back to Home Page