Unusually cool temperatures have greatly delayed the development of the floodwater mosquito (Aedes vexans). Lower than usual densities of this mosquito has been indicated by surveillance collections. Adult mosquitoes caught in our light traps are in the single digits. Normally, we would see a significant floodwater mosquito hatch at the second week of May but very cool temperatures have delayed this mosquito about 2 weeks. This means that the mosquito outlook for the Memorial Day weekend should be below average if conditions hold. Culex mosquito numbers have also been below average due to low temperatures despite their early start.

Most of the District floodwater sites have already been treated with the insect growth regulator methoprene. As planned, more extensive use of this 30-day residual growth regulator for floodwater mosquito control will allow us to devote more time to early season Culex eradication. This is an important component of our West Nile Virus response targeting the early bird«mosquito amplification stage of WNV. We have already begun catch basin treatments for Culex ahead of our usual schedule.

My thanks to the villages that have responded to our request last year and have begun sending us new building listings. Numerous villages have already begun sending us new building listings keeping us updated on potential Culex production sites in building foundations. Foundations can accumulate rainwater and may produce thousands of mosquitoes under the right conditions. Building foundations holding water will be treated with the natural microbial insecticide Bacillus sphaericus which because of the recycling nature of this larvicide should persist until the water is removed from the foundation.

MOSQUITO VIRUS SURVEILLANCE IN ILLINOIS

Three crows in Illinois have tested positive for West Nile Virus in 2002 according to the Illinois Department of Public Health. Two crows were from Kane County collected May 2^nd & 9^th,, and one crow from LaGrange in Cook County collected May 15^th. Additional birds have been submitted from Cook, DuPage, Lee, Kendall & Knox counties. More/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.

Because of the cool weather we have been unable to collect enough Culex mosquitoes for testing at NWMAD. This is expected to change as temperatures rise and mosquito collections become more numerous. The latest information on mosquito testing for West Nile Virus and St. Louis Encephalitis can be viewed at the Districts website (www.nwmadil.com).

Important: NWMAD will ship birds out for testing if requested (resources permitting) providing that the suspected birds are positively identified as crows or blue jays dead less than 48 hours. Note: the state is no longer collecting raptors (i.e. hawks) or birds other than crows & blue jays for testing. Local health departments should refer to the memorandum from Carl W. Langkop, Chief Communicable Disease Section, and Linn Haramis, Program Manager Vector Control/Arbovirus Surveillance (IDPH) for bird submission details.

DEAD BIRD SURVIELLANCE INFORMATION:

Cook County Department of Health is coordinating dead bird collections. Health Departments should contact the WNV Program Manager LaTrice Porter-Thomas (708-492-2035) if they have any questions regarding dead bird surveillance. As before, residents of the District should first contact their local Health Department if they find a dead blue jay or crow.

NOTE: Although there is a restriction on the number of birds Cook County was asked to submit for WNV testing it would be helpful to our District, for control purposes, if local Health Departments could send us weekly, dated address location lists of all reported dead blue jays & crows. This information would be useful for directing our control efforts after local Health Departments meet their bird testing quota.

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 for 7 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 stagnant water areas that remain wet for more than 7 days.

Mike Szyska

Director

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