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City to continue spraying operations for mosquitoes this week

Area mosquitoes are continuing to test positive for West Nile Virus.
Image by mika mamy from Pixabay.


The City of Longmont and Vector Disease Control International (VDCI) will continue spraying operations in local neighborhoods on Thursday, Aug. 11, weather permitting, to control the spread of West Nile Virus.

Area mosquitoes are continuing to test positive for West Nile Virus. Culex mosquito numbers are still elevated as the summer continues to be hot and dry.

Please avoid overwatering and discharging water into storm systems that can create stagnant water and Culex species breeding habitat. The City and VDCI will spray this week in the following zones: (The map of these zones can be found on VDCI's webpage.

  • Jim Hamm (LM-03)
  • Sandstone Ranch  (LM-22)
  • Union Reservoir  (LM-23)
  • Great Western/Mill Village (LM-27)
  • St. Vrain Greenway (LM-28)
  • Creekside  (LM-31)
  • Renaissance  (LM-34)
  • Rough & Ready South (LM-43)

Culex mosquitoes are the primary carriers of West Nile Virus, which they transfer to humans and other animals through bites. Spraying is triggered when West Nile Virus positive mosquitoes are discovered in Larimer, Boulder or Weld Counties and when Longmont traps exceed 150 mosquitoes per trap.

Boundaries of the predetermined spray areas can be seen on a map provided by the City and VDCI on the West Nile Virus webpage. When the triggering events occur, notice is provided on this webpage on Tuesdays that spraying will occur later that week – typically on Thursday evenings — giving residents 48-hours notice of any spraying.

Boulder County Public Health and Longmont officials urge residents to take necessary precautions to protect themselves. Keep safe this summer, and remember the 4Ds:

  1. Use DEET-enhanced insect repellent or alternative.
  2. DRESS in light colors and loose fitting long sleeves and pants,
  3. Avoid the outdoors from DUSK until DAWN.
  4. DRAIN standing water outside your home.

Managing Mosquitoes and Preventing the Spread of West Nile Virus

The City of Longmont has contracted with VDCI to implement an "integrated pest management program" to combat mosquitoes that might carry the West Nile Virus. This program focuses on first attacking mosquitoes in their larval stage before they become airborne. This is the best method since it eliminates mosquitoes before they hatch. This method also minimizes fogging to kill the adult, airborne bugs. However, some localized spraying becomes necessary when the West Nile mosquito population increases due to habitat and weather conditions.

VDCI uses state-of-the-art technology, calibrated application timing, and least-toxic products to minimize non-target impacts. All adult mosquito control is accomplished using Ultra Low Volume (ULV) fogging equipment and is performed after dusk when the majority of mosquito species are most active.

Residents Can Receive Notifications Related to West Nile Virus

VDCI maintains a database of Longmont residents who have made notification or shutoff requests for their property if spraying is scheduled. There are three options:

  1. Call Notification Only: VDCI will phone you before spraying in your neighborhood
  2. Address Shutoff Only: VDCI will shutoff the spray machine while driving past your property
  3. Notification & Shutoff: VDCI will phone you before spraying in your neighborhood and shutoff the spray machine while driving past your property

Please contact VDCI to make a notification or shutoff request by calling 877-276-4306 or visiting

The City also offers an eNotification system that provides residents with up-to-date information on a variety of topics including West Nile Virus. Visit the eNotification subscription page to sign-up and choose the West Nile category to receive notification when Local Spraying Alerts are issued.

General Info on West Nile Virus

WNV is transmitted to humans from the bite of an infected female mosquito. While most infections are mild, the more serious infections can cause encephalitis (inflammation of the brain) and/or meningitis (inflammation of the brain's lining), loss of vision, paralysis, coma, tremors, convulsions, and death.

Symptoms of WNV include fever, extreme fatigue, headache, body aches, and occasionally can also include skin rashes and swollen lymph nodes. Generally, symptoms appear 3 to 14 days after being bitten by an infected mosquito. Anyone who experiences these symptoms should consult their health care providers. There is no treatment, cure, or human vaccination for the virus. Health care providers can only treat the symptoms to help patients feel better and possibly recover more quickly.

Generally, the mosquito season extends from late April until mid-October, with the end of the season usually signaled by the first hard freeze in the fall.

For more information about West Nile Virus, mosquito activity in Boulder County, or proactive steps to take, call the Colorado Health Information Line at 1-877-462-2911 or  visit Boulder County's West Nile Virus webpage. To report nuisance mosquitoes, click on “Report Mosquito Activity” in the “What You Can Do” section on the website.

Learn more about West Nile Virus, the City’s integrated pest management program and how to protect yourself from West Nile Virus on the City's West Nile Virus webpage or by calling 303-651-8416.