Mosquitoes and Gardening

West Nile virus is a disease that targets primarily birds, horses, and humans. It is transmitted through the bite of a mosquito that has previously bitten a diseased bird. Most mosquitoes in the Chicago area are annoying but pose no serious health hazard. The Illinois Department of Health reports that the chance of contracting the disease from a mosquito is very slight, and that less than 1 percent of people who are bitten and contract the virus will become seriously ill.

Gardens and gardening are among the great joys in life. Mosquitoes can take a bite out of this pleasurable pastime unless preventive strategies are taken to minimize problems. 

Chicago Botanic Garden Recommendations
The following preventative steps can be taken to eliminate mosquitoes in gardens. 

ELIMINATE AREAS OF STANDING WATER 
Efforts should be focused on preventing adult mosquitoes from breeding. During warm weather, mosquito eggs can develop into larvae and then into adult mosquitoes in water that has been left standing for seven to ten days. 

Beginning in April until the first hard frost, weekly check your property, garden, alley, home exterior, and garage for any standing water or debris that might hold even the slightest amount of water. Household items might include cans, rain barrels, tires, buckets, garden tools, wheelbarrows, plant pot saucers, and children’s toys. The following precautions can also prevent the breeding cycle:

  • Seal any hollowed areas of tree stumps.
  • Repair outdoor leaky faucets to prevent small pools of water from forming.
  • Empty outdoor pet water bowls daily.
  • Repair torn screens or loose windows.
  • Clean gutters of all debris so rainwater never pools.
  • Check flat roofs for low spots that retain water.
  • Empty wading pools once a week. Store indoors when not in use.
  • Cover all larger pools if you are away for more than a week. Make sure pool covers do not accumulate water.
  • Change water in birdbaths at least once a week.
  • Install small pumps in ponds, aquatic gardens, or fountains to aerate water, or add larvae-eating fish. Commercially available “mosquito dunk” products are composed of bacteria, Bacillus thuringiensisvar. israelensis (Bti), that feed on mosquito larvae. This product is nontoxic to other insects, birds, or fish.
  • Empty outdoor fountains if you will be away for more than a week.
  • Check sewer drains, septic tanks, and downspouts for any pooling water.
  • Cover rain barrels with tight-fitting lids or 16-mesh screening.

WEAR PROTECTIVE CLOTHING AND REPELLENTS 
Wear socks and shoes, long pants, and long-sleeved, light-colored shirts when outside. Protect children and babies with proper clothing and mosquito netting.

Consult your family doctor for recommendations of mosquito repellents appropriate for you and your family. Research indicates that repellents containing 30-percent DEET offer adequate protection against mosquitoes. Consult a pediatrician for appropriate and safe children’s products. As with all insecticides, read and follow label directions.

PLAN YOUR GARDENING 
Mosquitoes are most likely to bite during the hours immediately before and after dawn and dusk. Plan your gardening to avoid the times when mosquitoes are most active. If virus-infected mosquitoes have been reported in your area, consider staying indoors during their peak biting hours. Mosquitoes favor shady, moist areas of a yard and rest in dense shrubbery; they are active from spring to the first hard frost in the fall.

Please contact Plant Information Service at (847) 835-0972 or via e-mail atplantinfo@chicagobotanic.org for more information about West Nile Virus and mosquito treatment in your area.