NUISANCE MOSQUITO CONTROL

An estimated 10-13 inches of rain fell within the NWMAD territory producing 2 enormous, successive emergences of the nuisance floodwater mosquitoes during August and the first week of September. Rains in September have not produced another significant emergence due to lesser rainfalls not reaching previous 5 inch rain water levels to hatch more floodwater mosquito eggs. Additionally, shorter daylight hours and cooler temperatures are initiating diapause in mosquitoes progressively reducing their blood feeding activity. The first brood of nuisance mosquitoes from August has been reduced by control practices and natural die-off. The last emergence in August has been further reduced by control but will still continue to make its presence known over possibly the next 2 weeks depending on prevailing temperatures.

Adult night time mosquito spraying will continue as long as weather permits and surveillance traps and virus testing warrants. Nuisance mosquitoes are still present in high numbers requiring additional treatments. Floodwater mosquitoes may remain active until the first hard freeze kills them.

DIRECTOR’S NOTE: I wish to personally thank all the efforts of the Cities, Villages, Municipalities, Health Departments and the multitude of other agencies that have endured the public complaints spawned by the enormous floodwater mosquito invasion. The combination of a WNV outbreak and enormous floodwater mosquito emergence posed a truly exceptional mosquito control task unlike any event our District has experienced in the past! Record rainfall events (near weekly) & flooding in August causing multiple nuisance mosquito emergences almost perfectly coinciding with mosquito developmental cycles that continuously augmented mosquito populations making our control efforts a truly daunting task. I appreciate everyone’s patience during this difficult time.

Biting floodwater mosquitoes that are very annoying will likely alarm the public as human WNV infections are also concurrently reported by health officials. Floodwater mosquitoes have not been implicated in the transmission of WNV to humans. Since it is unlikely that the residents of the District will be able to identify what mosquito species is actually biting them it would still be most prudent to encourage mosquito avoidance, control and self-protection to reduce the risk of infections. Please see NWMAD mosquito protection advice at: http://www.nwmadil.com/protecting yourself.htm.

CULEX MOSQUITOES

Culex mosquito numbers are below normal for this time of the season. Residents are strongly advised to inspect & eliminate all stagnant water areas from their properties that may produce these mosquitoes every week through the months of July-September. Any container that holds water and organic debris for greater than 7 days can produce many of these mosquitoes.

Stagnant water mosquito producing sites (detention/retention ponds, ditches, building foundations & container sources) will be treated with the insect growth regulator methoprene (Altosid). Treatment of stagnating floodwater areas has been an intensive process given all the water out there.

ADULTICIDING (Night Spraying Operation):

Night spray operations for medically important mosquitoes and the nuisance variety have been stalled this week due to inclement weather conditions (i.e. colder temperatures, wind and precipitation events). Spraying is likely to continue due to significant numbers of floodwater mosquitoes still throughout most of the District.

Listed below are the dates NWMAD performed night spraying (Adulticiding) operations in the Townships (or portions thereof). Night spraying operations are prioritized in order of: arbovirus infected mosquitoes; clusters WNV infected birds & sentinel mammal infections, high vector mosquito populations, excessive nuisance mosquitoes.

Barrington Township: 8/13, 8/21, 8/29, 9/5

Elk Grove Township: 8/2, 8/13, 8/16, 8/21, 8/28, 9/5

Hanover Township: 8/14, 8/16, 8/27, 8/28, 9/7, 9/13

Maine Township (incl. portion of Norwood Twp): 8/1, 8/14, 8/27, 8/28

Northfield Township: 8/1, 9/7

Palatine Township: 8/13, 8/21, 8/29, 9/4

Schaumburg Township: 8/13, 8/14, 8/28, 8/29, 9/4, 9/5, 9/13

Wheeling Township: 8/1, 8/2, 8/14, 8/16, 8/21, 9/5, 9/13

Nightly spraying schedules can be viewed at the following website: http://www.nwmadil.com/nitespry_map.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

The Illinois Department of Public Health (IDPH) reports: 34 counties with humans, mosquitoes or birds testing positive for WNV. There are 28 human cases (11-Suburban Cook County, 3-Chicago) of WNV and 833 WNV positive mosquito samples reported from Illinois. Thus far IDPH has reported 30 birds infected with WNV.

To Date NWMAD has tested (VecTest/PCR) 749 batches of mosquitoes for West Nile Virus, St. Louis and Western Equine encephalitis. 108 WNV infected batches of mosquitoes have been collected in NWMAD gravid traps to date. Mosquito batches testing positive in the District are posted at the NWMAD website http://www.nwmadil.com/VECTEST1.htm.

DIRECTOR’S NOTE: Typically, onset of human infections in past WNV years has followed close to a normal bell curve with the downside of the curve representing decreasing human cases primarily through the later half of September and/or sometimes into early October. Exceptions may happen as in 2003 & 2004 when a secondary infection peak may occur in September due to abnormally warm temperature periods extending the infection period. Technically, infection can conceivably occur anytime an infected mosquito with sufficient viral levels bites regardless of temperature, but in general, the warmer the temperature the more active mosquitoes bite and the less likely people are to be wearing protective clothing. For this reason it is still important to preach mosquito avoidance even though infections are less likely as we move into autumn. As we progress towards autumn Culex mosquitoes also gradually enter diapause thus reducing their blood feeding activity in preparation for winter hibernation. However, biting still may occur even into October with the cooler temperatures sometimes even attracting Culex pipiens into warm households and thus giving reason to its common name designation- the northern house mosquito!

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, tarp covers, 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.