[BoulderCouncilHotline] City Mosquito Management Program

[Abernathy, Rella]

Dear Council and Hotline Followers,

The city manager requested that I provide council with clarification about the city's mosquito management program, including the timeframe for when monitoring and treatment begins.

The city's mosquito program addresses two separate components-mosquitoes that have the potential to transmit disease to people (vector mosquitoes) and mosquitoes that do not transmit disease (nuisance or non-vector mosquitoes). The foundation of the city's program is based on vector mosquito management. Nuisance mosquito management began in 2007 in areas of high mosquito activity around city recreational facilities, and two neighborhoods that consistently experience high mosquito activity, Greenbelt Meadows and San Lazaro, were included in 2009.

Timing of Mosquito Monitoring and Treatment
The behavior and peak emergence patterns of vector and nuisance mosquitoes are somewhat different, with nuisance species becoming active earlier in the season.  Therefore, the two programs have different timelines, which are outlined below.


  1.  Nuisance Mosquitoes: Monitoring and treatment for the nuisance program begins in April and adult nuisance mosquito monitoring begins the first week of May. Most years, early trapping shows very little mosquito activity. In warm weather, nuisance mosquitoes can become active earlier in May.


  1.  Vector Mosquitoes: Surveillance of the Culex mosquitoes, that can potentially become infected with and transmit West Nile virus, begins the first week of June. The percentage of Culex is low in early spring and activity usually peaks in July. Although overall mosquito activity slowly decreases from August through September, the percentage of mosquitoes that are Culex species can increase during this period.  Council is updated each week from the beginning of June through September with information about West Nile virus mosquito testing, human cases and overall mosquito activity. There is a grid of mosquito traps that was designed specifically for the West Nile virus management program. The total numbers from these traps are reported each week. A subset of these traps (sentinel traps) are sampled and vector mosquitoes tested for West Nile virus infection. It's important to note that the majority of time, the weekly mosquito samples are negative. We assume West Nile virus is present at some level every year, but not all mosquitoes are vector species and not all vector mosquitoes are infected.

Greenbelt Meadows: Due to the high mosquito activity in Greenbelt Meadows residents have requested that the city take steps to lower mosquito activity in that area. The city has been responsive to these requests and included Greenbelt Meadows in the nuisance program in 2009, installed an adult mosquito trap in the neighborhood to monitor mosquito activity, expanded the radius of nuisance larval site treatments, inspected the irrigation system, cleaning and maintaining it and worked with lessees to schedule irrigation water release to reduce standing water in the fields. The city's mosquito contractor regularly inspects the area to determine if any new breeding sites have developed, double-check that larval treatments have been effective and watch for areas where adult mosquitoes can concentrate.

The majority of the mosquitoes trapped in Greenbelt Meadows are nuisance mosquitoes. While the average number of Culex mosquitoes in the city's grid of surveillance traps for 2017 averaged 28%, Greenbelt Meadows averaged less than 5%. This is an important distinction because Culex species tend to travel short distances from larval emergence sites, while nuisance species can travel many miles-some up to 25 miles. Although the city works every season to reduce local mosquito breeding around Greenbelt Meadows, the mosquito activity in the neighborhood reflects the overall mosquito activity in the surrounding region. The intensity of mosquito activity throughout the Front Range is dependent on geographic location and overall regional mosquito activity.

More information:  Attached is the April 12, 2018 Information Packet memo. It provides more background information, as well as more information about the program assessment and the timeline for the update.

In June the city is hosting an Information Session that will include staff presentations, followed by an open house with information tables and subject matter expert staff. Staff will share information about mosquito ecology, the history of the mosquito program, what is currently being assessed and the timeline for the update of the mosquito program. The public is encouraged to ask questions and share their concerns and suggestions.

Information Session - Mosquitoes in Boulder: What the city and community can do to stay safe and co-exist with mosquitoes

Where:               Auditorium, Sustainability, Energy and Environment Community
University of Boulder East Campus
4001 Discovery Drive

When:                 Wednesday, June 6 - 5:30-7:30 p.m.


Rella Abernathy
Integrated Pest Management Coordinator
[Planning,%20Housing%2]
O: 303-441-1901
C: 720-234-3003
abernathyr at bouldercolorado.gov<mailto:abernathyr at bouldercolorado.gov>

Department of Planning, Housing + Sustainability
1739 Broadway | PO Box 791 | Boulder, CO 80306
BoulderColorado.gov/IPM<http://www.bouldercolorado.gov/>

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