NUISANCE MOSQUITO CONTROL

Nuisance mosquito (Aedes vexans) counts in our light traps are averaging in the low single digits. Disparate rainfall (8/3/04) throughout the District has produced minor, localized, floodwater mosquito populations. Recent rainfall (8/24-8/28) produced up to an additional 1.5” throughout the District. It is likely that nuisance floodwater mosquitoes will be produced from this rainfall, however, due to previously dry conditions it will be a light hatch as long as no additional rainfall occurs for several days. If additional rain falls and these nuisance mosquitoes complete their life cycle in the water before it dries down we can have a moderately heavy mosquito hatch.

Crews continue to treat floodwater areas with the insect growth regulator methoprene.

CULEX MOSQUITOES

Average Culex mosquito numbers collected from gravid traps have increased due to current temperatures. Elevated temperatures will hasten mosquito development as well as the risk for West Nile Virus (WNV). Recent rainfall will create additional Culex mosquito production in standing water areas other that the storm sewer drains likely increasing the numbers of this species. As the Culex population increases so does the threat of West Nile Virus.

Crews are in the process of retreating catch basins with the microbial insecticide Bacillus sphaericus and methoprene in areas where West Nile Virus infected mosquitoes are consistently found. Other above ground stagnant water mosquito producing sites (detention/retention ponds, ditches/culverts, building foundations & container sources) are/will be treated with the insect growth regulator methoprene.

DIRECTOR’S NOTE:

Up until now conditions have been very dry throughout the District. Recent rains will produce additional mosquito production areas. Culex mosquito production is likely to increase if rains continue and water areas last long enough for this species to complete its life cycle in 10 days or less depending on temperatures. This is important since 148 mosquito batches have tested positive for West Nile Virus in the NWMAD territory and the virus is widespread. Additional mosquitoes will increase the risk of humans acquiring the disease. RESIDENTS MUST INSPECT THEIR PROPERTIES AT THIS CRITICAL TIME FOR STANDING WATER ON A WEEKLY BASIS. INSECT REPELLENTS ARE STRONGLY RECOMMENDED IF RESIDENTS GO OUTDOORS DURING MOSQUITO BITING TIMES ESPECIALLY AROUND SUNSET AND DAWN.

ADULTICIDING (Night Spraying Operation):

Adulticiding throughout the District is continuing based on West Nile Virus surveillance on batches of Culex mosquitoes. The majority of the eastern half of the NWMAD has been adulticided an additional three times since the last Newsletter update. This is necessary due to the numbers of WNV positive mosquitoes detected. The remainder of the District has been adulticided 1-2 times either for Culex or early season nuisance control.

Nightly spraying schedules can be viewed at the following website: http://www.nwmadil.com/District_map1.html. Alternately, a recorded phone message describing our scheduled nighttime spray program can be reached at (847) 537-2306 and pressing “5” on your telephone keypad. More information regarding our Adulticiding program may be viewed at: http://www.nwmadil.com/Night Spray info1.html

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

NWMAD has tested 534 batches of mosquitoes for West Nile Virus, St. Louis and Eastern Equine encephalitis. Collections have been from throughout the NWMAD territory. 148 of the batches tested since May were found positive for WNV. This represents a higher mosquito infection rate than the 2003 season.

Mosquito pools testing positive in the District are posted at the NWMAD website http://www.nwmadil.com/VECTEST1.htm.

DEAD BIRD SURVIELLANCE INFORMATION:

NWMAD has received 512 dead bird reports. Cities, villages and the public are encouraged to report dead birds to our District’s Dead Bird/Animal reporting web page, which can be accessed at www.nwmadil.com. Knowing this information allows our District to better focus our control efforts. The Cook County Department of Public Health is testing dead birds for WNV. Anyone wishing to have recently dead crows and blue jays tested for virus should phone the Cook County Department of Public Health at (708) 492-2650.

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 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 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 like tire casings, birdbaths, flower pots and barrels that may produce mosquitoes. Un-maintained swimming pools may produce thousands of mosquitoes. Call the District to report stagnant water areas that remain wet for more than 7 days. Additional mosquito avoidance/control practices may be found at the District’s website: www.nwmadil.com

Mike Szyska

Director

PLEASE FORWARD THIS INFORMATION TO APPROPRIATE DEPARTMENTS AND AGENCIES.