The Grand Forks Mosquito Control Program received overwhelming approval during a City of Grand Forks ballot measure on November 7, 1996. The citizens voted 91.8% to continue a mosquito control program implemented as a two year pilot test during 1995 and 1996. The program is designed to promote health and well being by reducing the risk of mosquito-borne diseases and reducing the nuisance level of mosquitoes in an environmentally sensitive manner.

The mosquito problem in Grand Forks is primarily generated by two types of mosquitoes, the floodwater (Aedes/Ocherotatus) and standing water (Culex) mosquitoes.  The plan to control these insects is based on an understanding of their life cycle, reproductive cycle, habitat, and range of travel.  A comprehensive mosquito control program employs all phases of mosquito control, such as source reduction, surveillance, larviciding, adulticiding (ground spraying), and public education.

The Aedes/Ochlerotatus mosquitoes lay their eggs on the ground in areas that are eventually covered with water at a later time.  The eggs need water to hatch into larvae and to continue their life cycle.  The mosquito remains in the larval stage for several days (3 – 10 days on average, depending on temperature and species) before transforming into the pupae stage.  The pupae stage is a resting stage for the mosquito before it transforms into an adult.  Once the eggs hatch, the cycle from egg to adult takes about seven to fourteen days in the Grand Forks area.  The time it takes for the mosquito to complete its life-cycle depends on the average temperature and species. The adult female mosquito mates almost immediately and then seeks a blood meal to nourish the eggs before laying additional eggs. The life cycle then begins again. Mosquito eggs can lie dormant for several years before receiving enough water to hatch. The female floodwater mosquito has an effective range of five to ten miles, but may travel as far as forty miles to obtain a blood meal.

The Culex mosquito, specifically the Culex tarsalis, has significance not only as a nuisance, but also as a potential carrier of the West Nile virus, St. Louis Encephalitis, and Western Equine Encephalitis, which can be deadly to humans.

The Culex mosquito lays her eggs in standing water.  The habitats generally preferred are open, sunny areas, but shaded areas with vegetation are also used.  The Culex mosquito is also a container-breeding mosquito.  Containers as small as a bottle cap may be successful in producing mosquitoes.  The egg to adult life cycle can be completed in seven to 10 days, dependent on the weather. The adult female mosquito may live approximately four to six weeks.  During this time seeking many blood meals and potentially laying thousands of eggs.  The Culex mosquito can travel several miles from a breeding site, but generally stays close to its origin.

The policy for adulticiding (spraying, fogging, etc.) in Grand Forks is determined by the surveillance division through several factors.  Thresholds have been established based upon surveillance and monitoring efforts for immature and adult mosquito populations using several types of indicators.  No one factor is always decisive for determining action.  Often times a combination of quantitative or objective data must be evaluated to make “spray/ no-spray” decisions.  Some of the factors considered prior to citywide spraying include; mosquito population, species diversity, mosquito-borne disease activity, community events, specific (public) events, weather conditions (short term and future weather conditions) and environmental factors.  The numeric values for the thresholds are subject to further refinement or modifications by the Mosquito Control Surveillance Division as circumstances or new information warrants.  As a result of the information gathered, a responsible decision can be made as to the timing and justification of a ground spray effort.  Without this information and guidelines, inappropriate spraying of pesticide throughout the city might occur.  This option contains a measuring device that is essential to any mosquito control program.

The public education program includes presentations, newsletters, TV commercials, radio, newspaper, etc.

The use of any type of insecticide may pose a certain amount of risk to the the public and the environment.  The insecticides used by Grand Forks Mosquito Control are cost effective and environmentally sound products which minimize the risk to the public and environment.  The intent of this program is to reduce the mosquito population without harming people or the environment.  While the Environmental Protection Agency considers the chemicals used in ground spraying safe for use as intended, we recommend people avoid direct contact with the spray.  Our staff are instructed to shut the sprayer off if they suspect there’s a possibility of the spray coming in contact with people. 

The type of products used in the ground spraying operations are synthetic pyrethroids. These products are toxic to adult mosquitoes.  Proper education and training help minimize the risk to the public and environment when using public health pesticides.

How do Integrated Pest Management programs work?

IPM is not a single pest control method but, rather, a series of pest management evaluations, decisions, and controls. In practicing IPM, growers who are aware of the potential for pest infestation follow a four-tiered approach. The four steps include:

(1) Action Thresholds: Before taking any pest control action, IPM first sets an action threshold, a point at which pest populations or environmental conditions indicate that pest control action must be taken. Sighting a single pest does not always mean control is needed. The level at which pests will become an economic threat is critical to guide future pest control decisions.

(2) Monitoring and Identifying Pests: Not all insects, weeds, and other living organisms require control. Many organisms are innocuous, and some are even beneficial. IPM programs work to monitor for pests and identify them accurately, so that appropriate control decisions can be made in conjunction with action thresholds. This monitoring and identification removes the possibility that pesticides will be used when they are not really needed or that the wrong kind of pesticide will be used.

(3) Prevention: As a first line of pest control, IPM programs work to manage the crop, lawn, or indoor space to prevent pests from becoming a threat. In an agricultural crop, this may mean using cultural methods, such as rotating between different crops, selecting pest-resistant varieties, and planting pest-free rootstock. These control methods can be very effective and cost-efficient and present little or no risk to people or the environment.

(4) Control: Once monitoring, identification, and action thresholds indicate that pest control is required, and preventive methods are no longer effective or available, IPM programs then evaluate the proper control method both for effectiveness and risk. Effective, less risky pest controls are chosen first, including highly targeted chemicals, such as pheromones to disrupt pest mating, or mechanical control, such as trapping or weeding. If further monitoring, identifications, and action thresholds indicate that less risky controls are not working, then additional pest control methods would be employed, such as targeted spraying of pesticides. Broadcast spraying of non-specific pesticides is a last resort.

Click here for more information about the Grand Forks Mosquito Control program.

Larvicides

• Altosid
• MetaLarv 

Adulticides

• Perm-X 30-30
• Zenivex
• DeltaGard

IS THE MOSQUITO SPRAY HARMFUL AND DO I NEED TO STAY INSIDE WHEN THEY SPRAY?

No, you don’t have to stay inside when the city is spraying for mosquitoes.  These products, when applied according to label will not harm people, pets, animals, or the environment. This public health pesticide is designed for use in residential and recreational areas. You are not required to leave an area when the sprayer goes by but you may want to avoid or minimize your contact with the cloud of droplets as it passes. If you prefer to stay inside with your windows and doors closed during the spray that’s fine, but it’s not necessary. Grand Forks Mosquito Control employees are trained and certified in the public health category as commercial pesticide applicators.

Citizens like to know if the products being used for controlling mosquitoes are safe for the public and the environment.  There are several factors that determine which products are used and how they will be used in Grand Forks.  The Grand Forks Mosquito Control program was developed utilizing the guiding principles of an integrated pest management (IPM) program. Our goal is to reduce the risk of mosquito-borne diseases and reduce the nuisance level of mosquitoes while maintaining the integrity of our ecosystem.  Environmental awareness is at the forefront of our program.  All products used in the Grand Forks program are registered and approved by the EPA and the North Dakota Dept. of Agriculture and our staff employs best management practices when using these products.  The Grand Forks Mosquito Control program was developed to improve the health and quality of life for the citizens in our community. At no time do we want to put anybody’s health at risk because of the products we use to control mosquitoes.  Following the guidelines of an IPM program permit us to use products that are safe to humans and the environment while reducing the risk of mosquito-borne diseases.

Are mosquito control pesticides safe?
Facts about mosquito control pesticide applications
Pyrethrins & Pyrethroids
Human exposure study
Truck mounted sprayers

Preventing West Nile Virus
The Facts about Mosquito Applications

• The Environmental Protection Agency (EPA) and U.S. Centers for Disease Control  and Prevention recognize  West Nile virus  as a serious  threat to the public  health and recommend an integrated pest management  (IPM) approach  to prevent the spread of the virus.  IPM encompasses West Nile virus surveillance and monitoring, sanitation, maintenance, biological and chemical control, and education of the public in prevention measures.
• Pesticides used in controlling mosquitoes that may carry West Nile virus fall into two categories: larvicides and adulticides.  Larvicides are applied to mosquito breeding grounds to kill developing larvae before they develop into adult mosquitoes.  Adulticides target adult mosquitoes and are applied as ultra-low volume (ULV) mist or fogs.  ULV sprayers dispense very fine aerosol droplets that stay aloft and kill flying mosquitoes on contact.  These products are designed to quickly break down into harmless chemicals in the environment.
• When it comes to West Nile virus, all IPM tools must be utilized to protect public  health, including the physical reduction of mosquito breeding  grounds, an effective  larviciding program,  the proper application of adulticides by well-trained personnel and the use of repellants by the public.  Collectively, these measures represent the only proven and responsible way to protect public health from the threat of mosquito-borne diseases.
• Mosquito control applications have been evaluated by the EPA and found to pose minimal risks to human health and the environment when used according to label directions.  For example, the EPA has estimated the exposure and risks to both adults and children posed by ultra-low volume (ULV) applications of the insecticides malathion and naled.  For all of the scenarios considered, exposures ranged from 100 to 10,000 times below an amount of pesticide that might pose a health concern.  These estimates assumed several applications over a period of weeks, and also assumed that a toddler would ingest some soil and grass in addition to skin exposure.  Other mosquito control pesticides pose similarly low risks. The EPA routinely monitors and evaluates pesticides to assure that products already on the market continue to meet scientific and regulatory requirements for health, safety and environmental effects.
• New technology is making mosquito control more precise,  accurate and safe.  Mosquito control agencies are using Global Positioning Systems (GPS) on fixed-wing aircraft to improve aerial applications and more accurately target mosquito populations while reducing non-target impacts.  Lasers are being used to measure droplet size of insecticide dispersed from aircraft, thus reducing the size of droplets dispersed and the amount of insecticide sprayed.  Wind tunnels are used to simulate flying conditions and enable quick and efficient testing of spraying systems to ensure optimal droplet sizes.  Night-vision goggles allow pilots to treat mosquitoes during evening hours when they’re most active and give pilots a better visual perspective to accomplish spray missions more efficiently.
• Mosquito control applications are highly  effective  in preventing the spread of West Nile virus, as evidenced  in the city of Fort Collins,  Colo.  The city implemented an emergency application program in August 2003 to combat an outbreak of the virus.  Before the applications began, 211 people in Fort Collins and its immediate vicinity had contracted West Nile virus.  After the applications, only 17 cases were reported in the area through the remainder of the season.  According to a report from the Centers for Disease Control and Prevention, the drop in cases in that city was far more dramatic than the gradual decrease in infection rates in the rest of the state.
• The public  supports the use of pesticides in preventing the spread of West Nile virus.  A November 2002 Harvard School of Public Health survey shows 9 out of 10 people in high- mosquito areas of the country favor spraying against mosquitoes to prevent the spread of the virus.
• Local election  results  reflect public  support for mosquito applications.  In a 2004 local election in Durango, Colo., residents in the Animas Mosquito Control District elected two write-in candidates who endorsed the use of pesticides in controlling the mosquito population and fighting the spread of the virus.
• Residents  of towns that make applications for mosquito control may follow  some common-sense guidelines to minimize  their exposure.  Generally, there is no need to relocate during mosquito control applications, but citizens may consult local media for announcements about mosquito applications and remain indoors when applications take place nearby.  Additional precautions include closing windows, turning off window-unit air conditioners when applications are taking place in the immediate area, and not allowing children to play near or behind truck-mounted applicators when they are in use.  Outdoor toys and play equipment may be brought indoors or wiped off with soap and water after applications.  Once the mosquito application – consisting of an insecticide mist — dissipates, it breaks down in the environment (generally within 24 hours) producing little residual effect.

What the Experts  are Saying

• “Contrary to the environmentalist view, public health campaigns that use insecticides against diseases have a remarkable record of public safety and a remarkable record of protecting humans from insect-borne diseases.”-Dr. Donald Roberts, professor of tropical public health, Uniformed Services University of the Health Sciences
• “Since West Nile virus is a mosquito-transmitted disease with no specific treatment, the only ways to control the outbreak are by personal protection from mosquito bites, including the use of repellents, and reduction in mosquito populations.” – Dr. Jerome Goddard, a medical entomologist and assistant professor of medicine at the University of Mississippi Medical Center in Jackson, Mississippi
•  “The reality is that the risk posed by West Nile virus is much greater than any risk associated with mosquito-control pesticides. The risks associated with proper use of pesticides are so low one cannot document any lasting effects. There are no known deaths from spraying these products. The same cannot be said for West Nile virus, which has affected more than 13,000 people and killed more than 500 in the U.S. since 2002.” – Allen James, president of RISE (Responsible Industry for a Sound Environment), an association of manufacturers of pesticide products used in and around homes, businesses and public areas that promotes the safe and responsible use of these products
• “Certain activist groups claim that pesticides are among the worst things facing civilization – right up there with the politically unpopular items like tobacco and guns. They say pesticide use should be avoided. I am convinced by the data and from my understanding of the EPA registration process that pesticides are generally safe for the public. In fact, they are applied at such low levels that there isn’t any measurable impact on humans.” – Dr. Jerome Goddard, a medical entomologist and assistant professor of medicine at the University of Mississippi Medical Center in Jackson, Mississippi

For more information about West Nile virus, visit  www.westnilevirusfacts.org. The site provides facts about the virus, dispels myths some people may have about it, and offers ways for people to prevent themselves and their pets from contracting it.

Mosquito Surveillance

Understanding the biology of the mosquito helps us control them successfully.  The Grand Forks Health Department has an active mosquito control surveillance program.  The Mosquito Surveillance Division is responsible for collecting, analyzing, and  recommending the type of action necessary to reduce the risk of mosquito-borne disease in our community.  Mosquito traps are distributed throughout the community.  The Information gained from these traps include:

Mosquito Population (daily trap count) – helps us determine the need to spray the city and lets us know if the spray was effective.

The types (species) of mosquitoes – Some mosquitoes are just annoying pests, but our region has the Culex tarsalis, the most common mosquito for transmitting West Nile virus.  We collect and test these mosquitoes to help us reduce the risk of this disease in our community.

Mosquito Activity – Knowing when the mosquitoes are most active is important for getting the best results from our spray.  To be effective, the mosquito needs to come in contact with the chemical and this happens best when the mosquito is in-flight.  Rotator traps are used to monitor the time mosquitoes are most active.

Gender Identification – Knowing the sex of the mosquito can be helpful in predicting a new hatch.  Male mosquitoes hatch out before females.  Therefore, if we see a spike in the number of male mosquitoes in the traps, we know there’s a potential for an increase of females.  That data is helpful in preparing us for a citywide spray.  It’s a short warning to get ready.

Source  reduction is removal or permanent  destruction of mosquito breeding sites. The larval habitats may be destroyed by  filling depressions that collect water, by draining swamps, or by ditching  marshy areas to remove standing water. Container-breeding mosquitoes are  particularly susceptible to source reduction as people can be educated to  remove or cover standing water in cans, cups, and rain barrels around houses.  Mosquitoes that breed in irrigation water can be controlled through careful  water management.

For some mosquito species, habitat elimination  is not possible. For these species, chemical insecticides can be applied  directly to the larval habitats. Other methods, which are less disruptive to  the environment, are usually preferred:

• Oils  may be applied to the water surface, suffocating the larvae and pupae. Most  oils in use today are rapidly biodegraded.
• Toxins  from the bacterium Bacillus thuringiensis var. israelensis (Bti) can be  applied in the same way as chemical insecticides. They are very specific,  affecting only mosquitoes, black flies, and midges.
• Insect  growth regulators such as methroprene are specific to mosquitoes and can be  applied in the same way as chemical insecticides.
• Potential  biological control agents, such as fungi (e.g., Laegenidium giganteum) or mermithid nematodes (e.g., Romanomermis culicivorax), are less  efficient for mosquito control and are not widely used. Likewise, mosquito fish  (including Gambusia affinis)  have largely been ineffective except in a few studies.

Theoretically, it seems that source reduction would  be an ideal approach to mosquito control: eliminate mosquitoes before they  reach the stage where they can transmit malaria.  However, larval habitats may be small, widely  dispersed, and transient. Anopheles gambiae,  one of the primary vectors of malaria in Africa, breeds in numerous small pools  of water that form due to rainfall. The larvae develop within a few days,  escaping their aquatic environment before it dries out. It is difficult, if not  impossible, to predict when and where the breeding sites will form, and to find  and treat them before the adults emerge. Therefore, larval mosquito control for  the prevention of malaria in Africa has not been attempted on a large scale.

More information available at Center for Disease Control and Prevention (cdc.gov)

Larviciding is the main component for a successful mosquito control program. Larviciding is the action taken to destroy mosquito larvae in stagnant water. Mosquito larvae left untreated develop into adult mosquitoes, which are a nuisance at best and a public health threat in the worst case.

Successful larviciding begins with an understanding of the type of mosquito present in our area. The Aedes vexans mosquito develop in stagnant water found in ditches and ground depressions which hold water for more than 7-10 days. Treating these sites with larvicides destroy the mosquito larvae.

Some of the larvicides used in the Grand Forks Mosquito Control Program include, Altosid and MetaLarv, (insect growth regulators). All mosquito control personnel are certified by the North Dakota Department of Agriculture.

The larviciding program begins in April and continues through September. In most areas larvicide applications are discontinued in late August, the residual life for most of our larvicides are 30-40 days which provides coverage until late September. September 20th is generally the date when the Grand Forks area can expect its first frost.

The larviciding program applies larvicides to stagnant water within the City of Grand Forks and the surrounding area. Seasonal employees are hired annually to apply the insecticides to areas of stagnant water. The employees inspect mosquito habitat sites and if necessary treat the sites with larvicide products.

The City of Grand Forks employs a comprehensive mosquito control program that’s comprised of 5 distinct sectors; surveillance, public education, larviciding, adulticiding, and source reduction.  Each sector plays an important role in reducing the risk of mosquito-borne disease and reducing the nuisance level of mosquitoes.  While most of our resources are expended in surveillance and larviciding, the adulticiding program is an important component of this program as this provides the direct means to control adult mosquitoes and reduce the risk of mosquito-borne diseases.  The public health pesticides used for adult mosquito control are registered by the EPA for use in residential, municipal, and recreational areas.  These products are applied either by aircraft or on the ground employing truck-mounted sprayers.  The City of Grand Forks primarily uses permethrin and/or etofenprox when ground spraying.

Mosquito adulticides are applied as ultra-low volume (ULV) sprays.  ULV sprayers dispense very fine aerosol droplets that stay aloft and kill flying mosquitoes on contact.  ULV applications involve small quantities of pesticide active ingredient in relation to the size of the area treated, typically less than 1.2 ounces per acre.

Adulticides can be used for public health mosquito control programs without posing risks of concern to the general population or to the environment when applied according to the pesticide label.

Citywide spraying will be considered when threshold criteria have reached the minimum action level.

Threshold:    Establishing a threshold for adult mosquito control is based upon surveillance and monitoring efforts for immature and adult mosquito populations using several types of indicators.  No one factor is always decisive for determining action.  Often times a combination of quantitative or objective data must be evaluated to make “spray/ no-spray” decisions.  Some of the factors considered prior to citywide spraying include mosquito population, species diversity, mosquito-borne disease activity, community events, specific (public) events, weather conditions (short term and future weather conditions) and environmental factors.  The numeric values for the thresholds are subject to further refinement or modifications by the Mosquito Control Surveillance Division as circumstances or new information warrants.

Synthetic Pyrethroids

• Permethrin, Resmethrin, Sumithrin for Mosquito Control
• Etofenprox

This information provided by the EPA and the Grand Forks Public Health Department-Mosquito Control.

The mosquito goes through four separate and distinct stages of its life cycle: Egg, Larva, Pupa, and Adult. Each of these stages can be easily recognized by its special appearance.

Egg : Eggs are laid one at a time or attached together to form “rafts.” They float on the surface of the water. In the case of Culex and Culiseta species, the eggs are stuck together in rafts of up to 200. Anopheles, Ochlerotatus and Aedes, as well as many other genera, do not make egg rafts, but lay their eggs singly. Culex, Culiseta, and Anopheles lay their eggs on the water surface while many Aedes and Ochlerotatus lay their eggs on damp soil that will be flooded by water. Most eggs hatch into larvae within 48 hours; others might withstand subzero winters before hatching. Water is a necessary part of their habitat.

Larva: The larva (plural – larvae) lives in the water and comes to the surface to breathe. Larvae shed (molt) their skins four times, growing larger after each molt. Most larvae have siphon tubes for breathing and hang upside down from the water surface. Anopheles larvae do not have a siphon and lie parallel to the water surface to get a supply of oxygen through a breathing opening. Coquillettidia and Mansonia larvae attach to plants to obtain their air supply. The larvae feed on microorganisms and organic matter in the water. During the fourth molt the larva changes into a pupa.

Pupa: The pupal stage is a resting, non-feeding stage of development, but pupae are mobile, responding to light changes and moving (tumble) with a flip of their tails towards the bottom or protective areas. This is the time the mosquito changes into an adult. This process is similar to the metamorphosis seen in butterflies when the butterfly develops – while in the cocoon stage – from a caterpillar into an adult butterfly. In Culex species in the southern United States this takes about two days in the summer. When development is complete, the pupal skin splits and the adult mosquito (imago) emerges.

Adult: The newly emerged adult rests on the surface of the water for a short time to allow itself to dry and all its body parts to harden. The wings have to spread out and dry properly before it can fly. Blood feeding and mating does not occur for a couple of days after the adults emerge.

How long each stage lasts depends on both temperature and species characteristics. For instance, Culex tarsalis, a common California (USA) mosquito, might go through its life cycle in 14 days at 70° F and take only 10 days at 80° F. On the other hand, some species have naturally adapted to go through their entire life cycle in as little as four days or as long as one month.

• All mosquitoes need water to complete their life cycle. It usually takes about 7-14 days for mosquitoes to complete their life cycle in the Grand Forks, ND area.

• Mosquitoes do not develop in grass or shrubbery. These areas are simply resting and shelter areas. Although floodwater mosquitoes may lay their eggs in grassy areas, they will not hatch out of the egg until they are joined with water. Mosquitoes generally take cover in shaded areas during hot sunny days to avoid the heat.

• Mosquitoes can fly considerable distance; some species remain close to their larval habitat, while other will fly 10 – 20 miles or more in search of food.

• Only female mosquitoes bite. Female mosquitoes draw blood for the needed protein enrichment required to lay eggs. Only after receiving a blood meal is a female mosquito capable of laying eggs. Male mosquitoes feed on nectar from plants.

• A female mosquito can lay up to 200 eggs at a time and these eggs can survive for several years before becoming emerged with water and hatching into the larvae stage. Some species of mosquitoes lay their eggs directly on the water’s surface; others leave their eggs in an area that will flood at a later date.

• Not all species of mosquitoes bite humans; some prefer birds, others horses, and some will bite frogs or turtles.

• Mosquitoes are responsible for more human death than any other living creature. In the United States mosquitoes are mostly a nuisance, however worldwide mosquitoes transmit disease to more than 700,000,000 people annually and will be responsible for the death of 1 of every 17 people currently alive *. The World Health Organization reports malaria causes as many as 3,000,000 deaths annually.

• There are approximately 170 species of mosquitoes in North America and as least 43 species of mosquitoes are known to occur in North Dakota.

• Each year thousands of dogs become disabled or die from lung, heart or circulatory problems caused by the heartworm disease. Mosquitoes can transmit this disease. This disease is also preventable with the proper prescription available from Veterinary clinics. Check with your veterinarian about heartworm testing and preventive medicine for your dog.

• Mosquitoes cannot transmit AIDS.

Grand Forks County has about 40 species of mosquitoes.  Of these 40, seven are of primary concern to Grand Forks Mosquito Control.  These are: Aedes vexans, Coquillettidia perturbans, Culex pipiens,  Culex restuans, Culex tarsalis, Culiseta inornata, and Ochlerotatus dorsalis.

Aedes vexans, is an aggressive biter and our most common floodwater species in Grand Forks.  This mosquito has the potential to fly several miles.  It can be a major nuisance problem throughout the season.  This species has not positively been identified as a high risk vector for humans, but it has been implicated as a secondary vector of dog heartworm.

Coquillettidia perturbans, also known as the cattail mosquito, is a mosquito that is often associated with aquatic habitats containing cattails.  It has tested positive for WNV in the United States.  It commonly takes blood meals from both bird and mammal species (including humans).  This is a one generation mosquito that usually hatches out in early July.  This mosquito over-winters in the larvae stage.

Culex pipiens, can be found in a fairly wide range of larval habitats but are generally associated with water that has a high organic content.  The species utilizes temporary ground water that ranges from mildly to grossly polluted.  The species also deposits its eggs in artificial containers including tin cans, tires and any refuse that allows stagnant water to puddle.  The species is decidedly urban and reaches greatest numbers in large urban centers.  Catch basins and storm drains provide ideal habitat for this species.  They are important vectors capable of amplifying WNV in the bird population.

Culex restuans, is found in similar breeding habitat as the Cx. pipiens.  It is a night time biter that feeds primarily on birds.  Laboratory trials show them to be moderately competent WNV vectors.  They are important vectors capable of amplifying WNV in the bird population.

Culex tarsalis, develops rapidly and produces multiple generations.  In the hot summer season, egg to adult development occurs in as few as four to ten days.  A female can lay six or seven times, with some 300 eggs in a batch.  Without control efforts, local populations can reach large numbers in a short time. This mosquito breeds in nearly every freshwater source except tree holes.  Culex tarsalis is the most efficient vector of mosquito-borne disease in North Dakota.

Culiseta inornata, Very large brown mosquito. Larval habitat includes ground pools, brackish ditches, and artificial containers. Occasionally bites humans, but not persistent biters. Eggs laid in rafts on water surface. Female overwinters as adult.

Ochlerotatus dorsalis, common floodwater mosquito and present most of the summer.  This species has the ability to migrate many miles in search of hosts, mates and/or oviposition sites.  Females are aggressive human biters. Their preferred hosts are large mammals, especially domestic animals and humans, but they will also feed on large birds.

Bionomics

• The larvae are found in clear or foul water in a variety of habitats including ditches, irrigation systems, ground pools, marshes, pools in stream beds, rain barrels, hoofprints, and ornamental pools.  Foul water in corrals and around slaughter yards appear to be favorite larval habitats in many localities.  Cx. tarsalis are biters, attacking at dusk and after dark, and readily entering dwellings for blood meals.  Domestic and wild birds seem to be the preferred hosts. and man, cows, and horses are generally incidental hosts. (Carpenter and LaCasse 1955:296)

Medical Importance

• Culex tarsalis is one of the most important vectors of arboviruses in the United States.  This mosquitoes is the most common species known for transmitting West Nile virus in North Dakota.  Cx. tarsalis are also believed to be the primary vector of St. Louis encephalitis and western equine encephalitis in the Dakotas.

Arboviral Encephalitides

Mosquito-transmitted viral diseases causing brain inflammation/encephalitis. Includes information on the diseases and their mosquito vector species

• Zika virus
• Eastern equine encephalitis
• Japanese encephalitis
• La Crosse encephalitis
• St. Louis encephalitis
• West Nile virus
• Dengue Fever
• Malaria

What Can I Do to Prevent WNV?

Prevention measures consist of community-based mosquito control programs that are able to reduce vector populations, personal protection measures to reduce the likelihood of being bitten by infected mosquitoes, and the underlying surveillance programs that characterize spatial/temporal patterns in risk that allow health and vector control agencies to target their interventions and resources.

The easiest and best way to avoid WNV is to prevent mosquito bites.

• When you are outdoors, use insect repellent containing DEET.  Follow the directions on the package.
• Many mosquitoes are most active at dusk and dawn.  Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
• Make sure you have good screens on your windows and doors to keep mosquitoes out.
• Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets and barrels.  Change the water in pet dishes and replace the water in bird baths weekly.  Drill holes in tire swings so water drains out.  Keep children’s wading pools empty and on their sides when they aren’t being used.

Myth #1: There’s not much I can do about West Nile virus.
Truth: There is a lot that you, personally, can do to reduce your chance of getting West Nile virus infection.

• Make it a habit to apply mosquito repellent with DEET when you’re spending time outdoors. This will reduce the number of mosquito bites you get.
• Mosquitoes are usually most active from dusk to dawn. Pay close attention to protection during these hours, or avoid being outdoors if possible.
• Reduce mosquito breeding habitat around your house.  The species of mosquito most common for transmitting WNV generally stays close to the habitat that it hatched from.
• Eliminate any standing water that remains longer than 7 days.   Inspect your yard once a week: get rid of containers that aren’t being used, empty water from flower pots, change water in bird baths and maintain clean gutters.

Myth #2: Kids are at the most danger of getting sick from West Nile virus.
Truth: People over 60 are at the highest risk for developing severe West Nile disease.

• Relatively few children have been reported with severe West Nile Virus disease. By contrast, most of the deaths due to WNV were among people over 60 years old.
• It is always a good idea for children to avoid mosquito bites, but it’s also important for adults – especially older adults – to take steps to avoid mosquito bites.

Myth #3: It’s only people who are already in poor health who have to worry about West Nile virus.
Truth: Healthy, active older adults who spend time working and exercising outdoors have been affected by severe West Nile virus infection.

• Being over 60 is a risk factor for developing severe West Nile disease if infected with the virus. There is a risk of getting mosquito bites while leading an active life outdoors. This doesn’t mean you have to stay inside – it does mean that it’s important to use repellent when you go outside.

 Myth #4: Repellents containing DEET are not safe.
Truth: Repellents containing DEET are very safe when used according to directions.

• Because DEET is so widely used, a great deal of testing has been done. When manufacturers seek registration with the US Environmental Protection Agency (EPA) for products such as DEET, laboratory testing regarding both short-term and long-term health effects must be carried out.
• There are products with different strengths (percentage of DEET) available. The longer the protection you need the higher percent of DEET needed.
• Repellent with DEET can be used for both adults and children, according to directions.

Myth #5: As long as my area has a mosquito control program, I don’t have to worry about using repellent.

Truth: Mosquito control activities don’t eliminate every mosquito, so personal protection is still important.

• Grand Forks Health Department maintains a proactive mosquito control program designed to reduce mosquito populations and mosquito-borne diseases.  However, this program cannot eliminate all mosquitoes. Personal protection, such as using repellent, keeping window screens in good condition, and control of household breeding sites are important steps for the public.
• Grand Forks currently has a very low population of nuisance mosquitoes.  This gives a false impression about the risk of WNV.  Even though there are very few mosquitoes in our community, the risk of WNV is still elevated.  Please take the necessary precautions to avoid mosquito bites.

5 Myths about West Nile virus