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  City of Loveland's Environmental Mosquito Management Program

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The City of Loveland Mosquito Management Program

1In 2013, The City of Loveland Mosquito Management Program completed its 27th year of cost effective Integrated Mosquito Management operations with Colorado Mosquito Control (CMC) as its contractor. Mosquitoes are dynamic insects which are capable of rapid populations increases dependent on habitat, water level, rainfall events, and temperature patterns. The experience and knowledge possessed by CMC employees of the local landscape and irrigation patterns, enables an overall reduction of mosquitoes within city limits. The biorational management operations and data driven response to spikes in mosquito abundance are aimed at reducing the risk and annoyances associated with mosquitoes.  If left unmanaged residents residing throughout large sections of the town would be burdened by mosquitoes, thereby resulting in a decreased quality of life and reduced ability to enjoy outdoor activities.

The primary objective of City of Loveland Mosquito Management Program is to employ trained field biologists to suppress the development of larval mosquitoes in the aquatic habitats. CMC prioritizes, at minimum 90% of resource allocation on larval control efforts. Surveillance monitoring of adult mosquito populations is performed to determine the need to reduce the adult populations via adulticiding materials, when needed. This goal enables a reduction in both the overall mosquito populations and the threat of mosquito borne disease transmission at the least possible cost, while minimizing the impact on the people and natural environment.

CMC maintains its commitment to offer environmentally sensitive and technologically advanced integrated mosquito management programs to its customers and community residents.  CMC works diligently to maintain the cooperative efforts for mosquito control and epizootic response management between the City of Loveland, Larimer County Department of Health & Environment, and surrounding local municipalities. The value of this cooperative program and its underlying data sharing and communications in the interest of public health cannot be over-emphasized. Please call 970-962-2583 or 970-962-2582 to report any water that stands for more than 4 days, mosquito annoyance concerns, or for information regarding West Nile Virus prevention. Resident phone calls continue to locate new mosquito habitats, thereby reducing the number of mosquitoes in the backyards of Loveland residents.

View the 2014 Annual Report for Mosquito Control in Loveland

Loveland Service Area
2The larval control area for the City of Loveland encompasses approximately 80 square miles within and surrounding the town limits of Loveland. Although many mosquito production sites are outside the city limits, they are well within the flight range of most mosquitoes. Larval control work outside the town limits will continue to remain a critical part of the overall operations of CMC.
Studies have indicated that adult mosquitoes can travel several miles in search of a blood meal and new habitats for offspring. Mosquitoes can be attracted from outside town limits into a more favorable environment inside town limits by factors including carbon dioxide, protection from wind, a nutrient rich larval site and harborage from heat. Mosquito reduction by Colorado Mosquito Control across the cities within Larimer and Weld Counties greatly reduces transient mosquito populations, thereby protecting the public from West Nile Virus transmission and the nuisance associated with mosquitoes.

How Is The Mosquito Management Program Funded?

The City of Loveland Mosquito Management Program is funded by city residents through the city’s utility billing program.  If you refer to your storm water bill, there is a charge of $.80/month or $9.60/ year paid by city residents in the limits of Loveland.  The $9.60/year per lot funds the surveillance monitoring of larval mosquitoes in the water, the application of bio-larvicide control products, the monitoring of adult mosquito populations via mosquito traps throughout the town, and data driven response & control of adult mosquitoes through ULV fogging applications. The money collected from the utility billing program also funds all Loveland resident requests for CMC technicians to inspect resident properties and to provide fish for control of mosquitoes in ornamental ponds, where applicable. 

The History behind the City of Loveland's Mosquito Management Program
The Loveland field office was the first office established by Colorado Mosquito Control to perform mosquito management operations.  The program first began in 1986 in direct response to concerns voiced by city residents who wanted to spend time outdoors while minimizing chemical spraying within the city's neighborhoods. The City of Loveland responded to the interests of the public with a program designed by Lew Keenan and Dr. Richard Hayes which focused on reducing mosquito populations at the source…the aquatic larval habitats. 

Larval Control Operations
To date, CMC has mapped over 1,359 larval mosquito habitats within the service area for the City of Loveland.  There are presently 581 active sites, 388 mandatory sites (weekly or twice/week inspections based on seasonal potential) and 140 urban/ backyard sites included in the inspection and larviciding program for the City of Loveland. There were 32 new larval sites identified and added to the routine inspection program in 2013. Field technicians methodically inspect larval habitats twice a week, weekly, bi-weekly or post rainfall, as deemed necessary based off of historical data.  A technician may spend the day inspecting a variety of habitats ranging from urban mosquito breeding locations (storm drains, catch basins, wading pools, paddle boats & tire piles), as well as cattail marshes, stagnant ditches, reservoir edges and irrigated pastures.  Inspections are performed to determine whether larval mosquitoes are present or not at a site. Once the presence of mosquito larvae is confirmed, larvicides are applied.  This enables targeted control, while reducing the miles of city streets that need to be fogged for adult mosquitoes.

When properly carried out, by trained applicators, IPM programs return beneficial results in reduced pesticide use, reduced frequency of pesticide resistance, and reduced exposure to pesticides by the environment. The Mosquito Management Program offered by CMC follows successful IPM principles for cost effective, scientific methods of survey/inspection, evaluation, diagnosis, application and record keeping of materials used.
CMC’s favored method of larval mosquito control is through bacterial bio-rational products.  The main product used by CMC is a variety of naturally occurring soil bacteria, Bacillus thuringiensis var. israeliensis.  Bti as it is known has become the cornerstone of mosquito control programs throughout the world.  The benefits include its efficacy and lack of environmental impacts.  When used properly successful control without impact to aquatic invertebrates, birds, mammals, fish, amphibians, reptiles, or humans can be achieved.  A broad label allows for the use of this product in the majority of the habitats throughout the service area. Another bacterial product closely related to Bti is Bacillus sphaericus (Bs). In addition to all of the benefits of Bti, Bs is by definition a true biological control agent in that it remains in the system through multiple broods, or generations, of mosquitoes.  Unfortunately the residual benefit of the control comes at a cost in price of approximately three times that of Bti.

3Other larval control products include a growth regulators (methoprene, in the form of the product Altosid), mineral oils (BVA), and an organophosphate (Abate). Methoprene is a synthetic copy of a juvenile growth hormone in larval mosquitoes.  The hormone prevents normal development of the adult mosquito in the pupal stage eventually causing death.  While a good control product, the cost is prohibitive to be the predominant product in a large scale program.  Abate, the one chemical larval control product CMC uses, serves as an effective product, but label restrictions limit its use in many areas.  CMC limits the use of chemical larvicides to areas with little biodiversity, such as road side ditches, or areas which chronically produce large amounts of mosquitoes and use them only as a last resort when other solutions are not present.  The benefits of these products are the availability of 30 and 150 day formulations. Mineral oil is the only product effective on the pupal stage and therefore is an essential tool when pupae are found.

In 2013 Colorado Mosquito Control performed 6,067 larval site inspections, of which 4,981 sites (82.1%) were wet upon inspection and 3,004 (60.3%) were producing mosquito larvae in the City of Loveland. An estimated 3.9 billion mosquito larvae were eliminated before emerging as biting adults via larvicide applications. CMC applied 10,370.9 lbs. of VectoBac (Bti), 628.3 lbs. of Vectolex (Bs), 2.2 lbs of Altosid, and 289.6 gallons of BVA mineral oil to 1,142.2 acres of 4lands in the City of Loveland.

In 2013 CMC performed 351 larval mosquito inspections at residential backyards and urban sites, of which 307 sites (87.5%) were wet upon inspection and 152 (49.5%) were producing mosquito larvae within the City of Loveland. An estimated 5.3 million mosquito larvae were eliminated before emerging as biting adults via larvicide applications. CMC applied 16.7 lbs. of VectoBac (Bti), 5.5 lbs. of Vectolex (Bs), 4.4 lbs. of Altosid, and 0.3 gallons of BVA mineral oil to 2.2 acres of backyards and urban lands in the City of Loveland.


In 2013 CMC performed 55 inspections of storm drain grids within Loveland, of which 92.7% were wet upon inspection and 94.5% were producing mosquito larvae or treated for the potential to produce larvae in the City of Loveland. An estimated 2.8 million mosquito larvae were eliminated before emerging as biting adults via larvicide applications at storm drains in Loveland. CMC applied 3.3 lbs. of Altosid and 0.8 gallons of BVA mineral oil to 1.1 acres of storm drains in the City of Loveland.

Mosquito Surveillance Operations
Information about mosquito abundance and species identity is critical to a successful mosquito control program.  Colorado Mosquito Control employs two kinds of traps to monitor mosquito populations.  The most commonly used is the CDC light trap which uses carbon-dioxide from dry ice as bait to attract female mosquitoes seeking a blood meal from a breathing animal.  Once attracted by the CO2, the mosquitoes are lured by a small light to a fan that pulls them into a net for collection. The gravid trap uses a tub of highly-organic water as bait to attract female mosquitoes that are looking for a place to lay their eggs. A fan placed close to the water surface forces mosquitoes that come to the water into a collection net.  Once back in the laboratory, the contents of the trap nets are counted and identified by technicians trained to recognize the Colorado mosquito species.

5In 2013, Colorado Mosquito Control monitored a statewide network of hundreds of weekly trap sites, collecting 334,005 adult mosquitoes that were counted and identified to species by the CMC Surveillance Laboratory. While individual traps provide only limited information, trap data is interpreted in the context of historical records for the same trap site, going back in time more than a decade.  Individual traps are also compared to other traps from around the region that were set on the same night and therefore exposed to similar weather conditions. Technicians working in the Surveillance Laboratory at Colorado Mosquito Control are trained to provide accurate species-level identification of mosquito specimens, for both adults and larvae. 
Additionally, the CMC Surveillance Laboratory conducts an intensive larval identification program with larval mosquito samples collected by I&L technicians prior to larviciding being identified to species. This information is now invaluable in targeting mosquito control efforts as we gain a greater understanding of the habitat types preferred by Colorado mosquito species and the seasonality of these habitats as sites for mosquito development. 
In 2013, an average of 37 surveillance light traps monitored adult mosquito populations within the City of Loveland. Surveillance trapping began the week of June 1st and full scale trapping was concluded on September 5th. There were 489 CDC light surveillance traps set during 2013 within City of Loveland, which collected a total of 23,170 mosquitoes. There was an average of 47 mosquitoes caught per trap per night and an average 33 Culex mosquitoes per trap per night. The composition of mosquitoes collected was 68.8% (15,941) Culex spp., 28.9% (6,706) Aedes/ Ochlerotatus spp. and 2.2% (516) Culiseta spp. Please refer to the Light Trap Genus Summary for a weekly breakdown of mosquitoes collected by trap location.

West Nile Virus Mosquito Results 2013

The Vector Index (VI) has been studied by the Centers for Disease Control (CDC) and CDPHE since the detection of West Nile Virus in 2003.  The Vector Index is widely applied in the assessment of West Nile Virus risk on a weekly basis across the State of Colorado.  As defined on the CDPHE website, The Vector Index (VI) is a measure of infection rate adjusted for Culex mosquito populations within a given area.  The value is an estimate of the number of West Nile Virus infected mosquitoes collected per trap per night.  The data suggests that a vector index of .75 or above is an indicator of high risk for West Nile Virus transmission to human in the area.

Many local health departments have moved towards mosquito-based surveillance indicators to assess the weekly risk of West Nile transmission and guide response decisions for mosquito adulticiding. The vector index and infection rate is derived by testing the collected mosquitoes from CMC surveillance trapping for WNV infection. This value is closely monitored by the CDPHE and local health departments to evaluate the risk posed by the vector mosquito population.     

6As defined in the CDC guidelines for West Nile virus surveillance, prevention and control (June 2013), the vector index (VI) is an estimate of the number of West Nile virus infected mosquitoes in an area. An operational value of 0.75, which was derived from comparison of historical data for human infections, as well as relative abundance and infection in mosquitoes, serves an indicator of high risk for West Nile virus transmission to humans in the corresponding area ( As the value of the vector index increases there is a corresponding risk of human disease and this value can be used to offset epidemics. 

In 2013, a total of 351 mosquito sample pools comprised of 1,984 Culex pipiens, 104 Culex spp., and 8,727 Culex tarsalis mosquitoes collected from surveillance traps in the City of Loveland were tested for West Nile virus at Colorado State University. Of these 351 sample pools, 291 were negative for West Nile and 55 mosquito sample pools were West Nile positive. There were 2 WN+ pools which were collected from gravid traps and 53 WN+ pools collected from CDC CO2 baited light traps in the City of Loveland. There were 213 WN+ mosquito sample pools identified from Larimer County in 2013.

Targeted Ultra-low Volume Adult Mosquito Control
Adult mosquitoes can come from unknown unidentified sites or may migrate in from uncontrolled areas. The City of Loveland uses all available data from CDC light traps, Mosquito Hotline annoyance calls, and field technician reports to focus adult mosquito control efforts on specific, very limited “targeted” areas. In parts of the community were high numbers of mosquito annoyance calls are received, “floater” CDC light traps are set to evaluate adult population levels and species make-up. In most cases, a direct correlation is evident between areas with high complaint calls and high trap counts. While this correlation allows us to focus adult control in these areas, the emphasis is placed on finding the source of breeding and continued larval control measures.

Over 95% of the City of Loveland’s mosquito control program is targeted against larval (aquatic stage) mosquitoes utilizing biological control materials, however on occasion adult mosquito spraying becomes necessary. At that point Colorado Mosquito Control utilizes 20% Permethrin in ultra low volume (ULV) spray applications via truck mounted fogging machines. ULV sprayers dispense an extremely small amount (0.0035 pounds per acre) of fine aerosol droplets which stay aloft and kill adult mosquitoes on contact.

Permethrin is a synthetic pyrethroid similar to the insecticide pyrethrum which occurs naturally in chrysanthemum plants. Permethrin is found in a variety of products, including household insecticides, flea dips, repellent for clothing, sprays for pets, and lice shampoos. This pesticide has been selected to achieve effective control of mosquitoes and suppression of West Nile Virus transmission with the least impact on human health and the environment.
Fogging applications are performed based on mosquito populations caught in traps on a nightly basis.   The city is divided into 36 zones with at least 1 trap per zone.  Specific neighborhoods are fogged when surveillance traps catch 100 floodwater mosquitoes, referred to as a “Nuisance Threshold” or 50 Culex mosquitoes, referred to as a “Disease Threshold”. The thresholds for fogging applications are established by an industry standard that measures vector and nuisance mosquito populations.

Notification and Shutoff Services
Upon request, residents can be notified prior to spraying with Permethrin insecticides.  Call & Shutoff forms are available online and may be submitted via CMC website or by mail. Please note that a shutoff does not guarantee that drift of insecticide material will not occur and may decrease the effectiveness of adulticiding on mosquitoes in your immediate area. Please note that the call shutoff list is a service that CMC provides to residents and may be obsolete in the case of a West Nile Virus Public Health emergency, as experienced in 2003/ 2007.  For additional information regarding permethrin, including toxicology data please visit: and click on the tab for pesticides.