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Mosquito Management

Learn About Our Mosquito Management Program


2023 Weekly Mosquito Monitoring Report

The Forest Preserve District began testing forest preserves for West Nile virus on June 1.

Week of Sept. 18

Positive Tests in Du Page Forest Preserves This Week


Forest Preserve District staff collected one positive sample this week. The sample was collected at Herrick Lake in Wheaton. (See the aerial maps of the positive location below.) Though infected mosquitoes were collected from traps at this location, the mosquitoes may have originated from off-preserve breeding sites. Known District breeding sites near positive samples are treated with a biologically derived larvicide to reduce the Culex mosquito population. Ongoing surveillance of these areas will continue in order to identify and treat all District locations that may be harboring Culex mosquito larvae.

Positive Sample Locations (PDF)

Total Positive Tests in Du Page Forest Preserves This Year


There have been a total of 23 positive West Nile virus samples in the DuPage forest preserves in 2023.

Positive Samples in Du Page County This Year


The DuPage County Health Department has reported 158 positive samples this year.

DuPage County Surveillance Maps

Reported Human Cases in Illinois This Year


As of Sept. 22, the Illinois Department of Public Health has reported 60 human cases of West Nile virus this year.

5 Human Deaths

36 Positive Birds

3,212 Positive Mosquito Batches

Illinois West Nile Virus Numbers At A Glance

Fight the Bite

Here are some simple, common sense precautions people can take to avoid mosquito bites and protect themselves against West Nile virus:
  • Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn.
  • When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that includes DEET, picaridin, oil of lemon eucalyptus or IR 3535 according to label instructions. Consult a physician before using repellents on infants.
  • Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.
  • Eliminate all sources of standing water that can support mosquito breeding, including water in bird baths, ponds, flowerpots, wading pools, old tires and any other receptacles. In areas outside of Forest Preserve property, contact your municipal government to report stagnant water in roadside ditches, flooded yards and similar locations that may produce mosquitoes.
  • Public health officials believe that a hot, dry summer could increase mosquito activity and the risk of disease from West Nile virus.