NUISANCE MOSQUITO CONTROL

Currently, nuisance mosquito (Aedes vexans) numbers in New Jersey Light traps are low. However this is likely to change due to significant rainfall on September 8^th (1”+) and massive rainfall on 12-14^th(7-10+”). It is likely that rain on the 8^th may produce a limited amount of nuisance mosquitoes noticeable around middle of next week depending on temperatures. Heavier rainfall September 12-14^th will likely produce a more significant brood of nuisance mosquitoes making their presence known the last week of September or later if temperatures drop. At this point in time floodwater mosquitoes also begin to enter diapause in preparation for the winter months. Typically, with the floodwater mosquito this means that a certain percentage of the eggs inundated with floodwater do not hatch but remain in the soil to await the spring rains in April.

Crews are continuing to treat floodwater areas with methoprene (Altosid) pellets. Flooded areas along the Des Plaines River and creek systems will be treated after floodwaters recede.

CULEX MOSQUITOES

Culex mosquito numbers are below normal. Despite the lower normal numbers the risk of WNV still remains and residents should continue to protect themselves against mosquito biting! 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 an abundance of these mosquitoes. Culex mosquitoes this time of the season will also be entering diapauses in preparation for the coming winter months.

Stagnant water mosquito producing sites (detention/retention ponds, ditches, building foundations, catch basins, & other container sources) will be treated with the insect growth regulator methoprene (Altosid) and mosquito larvicide oils.

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

The Illinois Department of Public Health (IDPH) reports: 20 counties with humans, mosquitoes or birds testing positive for WNV. There are 6 human cases (1-Cook, 1-Kane, 1-Du Page, 1-Montgomery, 1-Macon, 1-Whiteside County) of WNV and 482 WNV positive mosquito samples reported from Illinois. Thus far IDPH has reported 18 birds infected with WNV.

NWMAD has tested 685 batches of mosquitoes for West Nile Virus. 95 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.

ADULTICIDING (Night Spraying Operation):

Continuation of adulticiding is likely if virus activity continues to be demonstrated in the mosquito population and weather conditions are favorable.

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 DIAPAUSE

Portions of the Culex and nuisance floodwater (Aedes vexans) mosquitoes appear to be entering diapause in preparation for the winter months.

Although floodwater mosquitoes will not die-off until the first hard frost their mosquito larvae young are now not as abundant in water areas throughout the District. Typically, eggs laid in the soil by these mosquitoes will not hatch from floodwater areas due to the current shorter day length period. Shorter day lengths activate a sort of survival instinct that keep floodwater mosquito eggs from hatching even if inundated after heavy rains so that most of the developing mosquito larvae do not hatch in the colder months which would be detrimental if freezing conditions exist. In the spring, when longer day lengths return and after a rainfall, the surviving eggs will hatch and the floodwater mosquito cycle starts over again.

Culex mosquitoes, responsible for transmitting West Nile virus, have also started entering diapause in preparation for the coming winter months. Culex mosquitoes stop blood feeding and laying eggs when day length gets shorter. The adult Culex don’t die-off with the first hard frost, but, instead overwinter as adult mosquitoes in protected hibernation areas.

Please note that diapause is a gradual process in the mosquito population so residents are still advised to protect themselves from biting mosquitoes until freezing temperatures assure mosquito inactivity!

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.