Mosquito Meter

What is it?

The mosquito meter is a way for residents to monitor the risk of human West Nile infection.  It is important to remember that West Nile virus, and the mosquitoes that carry it, are in and around Colorado each year.  Residents are encouraged to use protective measures, regardless of meter level.

  1. DRAIN standing water on your property.
  2. DEET containing insect repellent when outside. (Picaridin, IR3535 or oil of lemon eucalyptus).
  3. DRESS in long sleeves and pants that have been sprayed with repellent.
  4. PROTECT by limiting exposure outside and check window screens.

The meter level is “low” this week. 

  • Lower than average number of mosquitoes trapped,
  • No new mosquitoes have tested positive for West Nile virus in Mesa County.

Residents should continue to take precautions to protect themselves from mosquito bites:

  • There has been confirmed human West Nile virus cases this season in Mesa County.
  • The season is at or near the historical end.

Human Cases of West Nile virus

2013 2014 2015 2016 2017 2018 2019 to date
Mesa 9 7 2 0 0 2 6
Delta 14 3 0 0 1 8 24
Montrose 2 1 0 0 1 4
Garfield 0 0 0 0 0 1 0

Partnership with Grand River Mosquito Control District

This data is collected in collaboration with our community partners at the Grand River Mosquito Control District.  It is because of this partnership that we’re able to provide real-time data on mosquito activity in the county. We’re grateful for their support and partnership to bring this important data to the community.  You can visit their website for more information.


Mosquito Meter:

The Mosquito Meter ranges from low to high using West Nile data collected from traps throughout Mesa County. In determining the level, a team at Mesa County Public Health considers: 1) the weather conditions including moisture and temperature 2) the number of mosquitoes trapped and how that compares to previous years 3) whether there have been any culex mosquitoes test positive for West Nile virus in the current season in our area and 4) if any confirmed human cases of West Nile virus have been reported in Mesa County.  Keep in mind, this risk can vary significantly from one area of the Grand Valley to the other and West Nile is in and around Mesa County each year.  Wearing repellent, and other protective measures are always the best choice, regardless of meter level.  Multi-county data is collected and retrieved from the Colorado Electronic Disease Reporting System (CEDRS).  Throughout the summer as new CEDRS data is updated,  our team will evaluate and update the Mosquito Meter to reflect current conditions.

Culex Mosquito Counts Around the County:

This map shows the number of Culex species mosquitoes caught in mosquito traps around Mesa County for the most recent week. The Grand River Mosquito Control District (GRMCD) collects mosquitoes from each trap every week to keep track of which species of mosquitoes are showing up and where. There are 28 different types of mosquitoes present in Western Colorado, the Culex species are the only mosquitoes that cause disease (West Nile virus). The size of the circle changes based on how many Culex mosquitoes were caught in that trap the previous week. A bigger circle indicates more disease-causing mosquitoes were collected from that trap.

Culex Mosquitoes Counts in Selected Traps:
This chart shows the number of Culex mosquitoes that have been collected in the trap that you select in the map above. If no trap is selected, the number of Culex species for all traps is displayed. Counts for that trap are shown for 2017, 2018, 2019, and the average number collected from 2014-2018. Mosquitoes are counted from each trap each week, however, only the number of Culex species mosquitoes collected are displayed as these are the only ones known to cause human disease in Western Colorado.
Week numbers are used so that weeks are comparable across different years. For reference, July 4th usually falls during week 27 every year. The current week number is also shown in the bottom right corner of the chart.