In the 2013 battle against blood-thirsty mosquitoes and West Nile Virus, Grand Prairie will ground spray every Thursday and Friday night, weather permitting, from May – October in neighborhoods testing positive for infected mosquitoes. This replaces the city’s previous process of issuing a news release for every positive test and related spray area.
Mosquito season has started early and so will the City’s annual Fight the Bite campaign. A DFW area city has already had multiple mosquito samples test positive for West Nile Virus. Grand Prairie has been trapping since April 1st but has not had any positive mosquitoes yet this season.
To know if your neighborhood is affected by spraying:
Click here for upcoming spraying locations
To be notified when new locations are scheduled for spraying, sign up for any of the following:
- Click here or call 972-237-7595 to subscribe to the City’s Reverse 911 call out system. Subscribers in affected areas will receive a phone call.
- Follow us at twitter.com/gp_tx. Alerts will be sent out that identify affected areas.
- Like the City’s Facebook page, Facebook/grandprairie. Posts will identify affected areas.
- Subscribe for email alerts on the City’s website, www.gptx.org/enotify. Emails will be sent that identify affected areas.
Grand Prairie Mosquito Program
Due to weather patterns observed this spring, the 2013 West Nile season is expected to be similar to last year. In 2012, there was a metroplex-wide increase in the number of mosquito samples testing positive for West Nile virus and cases of human infection. Click here for the season overview for Dallas County.
The City of Grand Prairie Vector Control Ordinance is available here.
Grand Prairie Statistics
Last year, Grand Prairie had 18 human and 11 mosquito West Nile cases. In an effort to manage the mosquito population and educate the public on this serious issue, the City of Grand Prairie took the following measures:
- Ground sprayed in response to positive human and mosquito positives in the City.
- Surveyed the areas where positives have been found.
- Crews have surveyed and are continuing to survey low lying areas for standing water. When possible mosquito habitat is found, larvicide is applied.
- Applied larvicide to over 20 areas throughout the city.
- Provided post cards and door hangers to over 1,700 residents with pools.
- Provided information to vulnerable populations.
Vector Control Program
The objectives of the City of Grand Prairie Vector Control program are to control nuisance mosquitoes, reduce the potential of mosquito borne disease transmission, and provide a comfortable and healthy atmosphere for community residents. We accomplish this task by using an Integrated Pest Management plan of attack. Integrated pest management is the combining of appropriate pest control tactics into a single strategy to reduce pests to an acceptable level. Using many different tactics to control a pest problem tends to cause the least disruption to the living organisms surrounding the treatment site.
Vector Surveillance Program
The Environmental Quality Division has an active vector control program to prevent mosquito-borne diseases. Each week, vector control personnel set traps throughout the city. Mosquitoes trapped at each location are prepare for shipment, and each "pool" of mosquitoes is sent to the Dallas County Health and Human Services Vector Control Lab and the Texas Department of State Health Services Arbovirus Lab for species identification and disease testing. Mosquitoes are tested for West Nile Virus (WNV).
When a “pool” of mosquitoes tests positive for West Nile Virus, the Environmental Quality Division personnel spray the area surrounding the site where the positive sample was trapped. The spraying takes place at night from a truck mounted sprayer.
Further mosquito trapping of the area is performed the following weeks to determine if the mosquitoes carrying the disease have been eliminated in the sprayed area. For more information, contact the Environmental Quality Division at 972-237-8055.
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Pesticides Used for Mosquito Control
What are the environmental impacts of larvicides?
The larval control products (Methoprene, Bti, and Bs) used by the City of Grand Prairie are target specific to mosquito larvae and black fly larvae. Methoprene (Altosid) is an analog of the Juvenile Hormone that acts as a growth regulator. The presence of Methoprene in a treated area does not kill mosquitoes, but will unable mosquito larvae to become adult. The bacteria contained in VectoBac (Bti) and VectoLex (Bs) occur naturally in the soil. Both of these soil bacteria can be processed through the systems of mammals, birds, reptiles, amphibians and nearly all aquatic invertebrates.
The main benefit for application of these products enables the reduction of mosquito larvae at a reasonable cost without negatively impacting the natural environment. There have been no notable implications associated with application of these larvicides to the natural environment.
What is permethrin?
Permethrin is an insecticide in the pyrethroid chemical family. Pyrethroids (also known as synthetic pyrethroids) are insecticides chemically similar to pyrethrins found in natural pyrethrum. Natural pyrethrins are extracted from the flowers of the chrysanthemum, which have been recognized for centuries for their insecticidal activity. Pyrethroids do not have the extent of adverse effects on non-targets unlike other insecticide groups.
Pyrethroids are widely used in public health applications because of their relative safety for humans, high insecticidal potency at low dosages and rapid knock-down effects. First developed in 1973, pyrethroids are more stable to light than natural pyrethrum. Permethrin was originally registered for use by the United States Environmental Protection Agency (U.S. EPA) in 1979, and was re-registered in 2006.
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What is permethrin used for?
Permethrin is registered for use on/in numerous food/feed crops, livestock and livestock housing, modes of transportation, structures, buildings (including food handling establishments), Public Health Mosquito abatement programs, and numerous residential use sites including use in outdoor and indoor spaces, pets, and clothing (impregnated and ready to use formulations).
According to Agency data, the EPA cites that approximately 2 million pounds of permethrin are applied annually to agricultural, residential and public health uses sites. The majority of permethrin, over 70%, is used in non-agricultural settings; 55% is applied by professionals, 41% is applied by homeowners on residential areas, and 4% is applied on mosquito abatement areas.
Permethrin is a restricted use pesticide for crop and wide area applications (i.e., nurseries, sod farms) due to high toxicity to aquatic organisms, except for wide area mosquito adulticide use. It is a general use pesticide for residential and industrial applications. Permethrin also has non-FIFRA pharmaceutical uses as a pediculicide for the treatment of head lice and scabies. The Food and Drug Administration (FDA) approves use of the pesticide-containing pharmaceutical under the Federal Food, Drug, and Cosmetic Act (FFDCA).
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How much product does City of Grand Prairie apply when spraying occurs?
When the City of Grand Prairie sprays for adult mosquitoes the applications rate of active ingredient is no greater than .007 lbs. per acre (AI)/acre). Most agriculture applications are performed at a rate of 0.2 lbs-0.4 lbs. per acre.
What are the effects on other insects from spraying?
Extensive studies have shown little effect on insects from Ultra Low Volume (ULV) fogging for adult mosquitoes. ULV applications use Ultra Low Volumes, i.e. less than 1.0 ounce per acre, in microscopic sized droplets of a low toxicity product. We can minimize the negative non-target effects through the combination of ULV technology, limiting applications to periods of high annoyance or disease threat, and selecting the period of the evening when many other non-target insects are not active. Please note that although permethrin does present toxicity to bees, many bees are not flying/pollinating at the time mosquito spraying is performed.
What are the effects of permethrin exposure in humans?
Pyrethroids do not accumulate in the body and their excretion is rather rapid, even after repeated administrations: typically, 90% of the administered dose is excreted in urine and feces within a week after treatment. In addition, Permethrin has been used for many years, with no human poisoning cases reported. No indication exists that permethrin has a significant adverse effect on humans when used as recommended. It has induced skin sensations and paraesthesia in exposed workers, but these effects disappear within 24-48 hours. Transient numbness, itching, tingling, and burning sensations have been reported in a small percentage of humans after dermal exposure to permethrin when it was used to treat head lice (World Health Organization, 1990).
With respect to mosquito applications, many people do not risk any exposure to permethrin if their windows are closed and they are within their homes during a mosquito spraying application. The ULV spray does not stay in the air for much longer than 2-3 hours. The product will adhere to vegetation and therefore, people are not breathing in permethrin from a mosquito control application the morning after an application.
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What is the half-life of permethrin?
In soil the average half-life of permethrin in aerobic soils is 39.5 days, with a range from 11.6 to 113 days. Permethrin binds tightly to soil and is broken down primarily by microorganisms, but also by photolysis.
When exposed to water some of the product is degraded. Some degradation also occurs due to sunlight while in the water column but the majority binds tightly to the sediment. The average half-life range for permethrin in the water column is about 19-27 hours, however permethrin adsorbed to sediments can persist more than a year. Permethrin is not likely to contaminate groundwater due to its low water solubility and strong adsorption to soil.
How much permethrin can people be exposed to?
The U.S. EPA has determined a Reference Dose (RfD) of 0.25 mg/kg/day for both acute and chronic dietary exposures to permethrin. The RfD is an estimate of the quantity of chemical that a person could be exposed to every day for the rest of their life with no appreciable risk of adverse health effects. The reference dose is typically measured in milligrams (mg) of chemical per kilogram (kg) of body weight per day. No human data were found on chronic effects of permethrin.
The U.S. EPA has not determined a Maximum Contaminant Level (MCL) for permethrin in drinking water. However, a limit of 0.3 mg/L was set by the World Health Organization (WHO) as a guideline for permethrin in drinking water when it is applied to water for mosquito control.
The Agency for Toxic Substances and Disease Registry (ATSDR) determined Minimum Risk Levels (MRLs) for oral exposures to technical grade permethrin of 0.3 mg/kg/day for acute oral exposures (up to 14 days) and 0.2 mg/kg/day for intermediate durations (15-364 days).
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Does garlic work as a repellent or insecticide?
Although garlic has exhibited some activity against mosquitoes, the active ingredient in garlic is Allicin. This chemical has an LD50 of 60 compared to permethrin, which has an LD50 of 4,000. Note that the lower the LD50, the more toxic the substance. We would suggest an EPA approved repellent for personal protection.
There is no research that directly supports the effectiveness of this product as an adulticide either. Garlic has not completed the registration process through the EPA and is not supported as a registered adulticide for adult mosquito control.
Is permethrin linked to the honey bee die off?
Funding has allowed for collaborative comparative studies to be initiated, including many professionals and experts from across the country to further investigate the phenomenon of Colony Collapse Disorder (CCD). CCD was largely documented in 2006 and was initially linked to varroa mites. Research on the declining bee population is only just beginning; with pathogens, environmental chemicals, and nutritional stressor being some of the most recent causes being considered. One class of pesticides under close scrutiny by beekeepers and the press are neonicotinoids, which are known to be quite toxic to honey bees. We strongly encourage you to review the current literature available to stay informed.
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Maintaining Your Pool
If you have a swimming pool on your property, you must know that dirty or unmaintained pools are the perfect place for mosquito breeding. Mosquitoes that carry the West Nile Virus lay eggs in pools with stagnant water. Swimming pools must be properly maintained according to the following maintenance tips:
• Run the pool filter daily about 8 hours per day.
• Maintain the pool’s sanitizer in the recommended range.
• Regularly clean, vacuum, and brush the pools walls and surfaces to remove bio-films.
• Add an initial dosage of quaternary algaecide.
• If the pool is covered, make sure the cover is completely drained of excess water.
• Delay winterizing the pool until first freeze.
• Make sure floats, equipment, and pool toys are stored so they will not collect water.
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Report Stagnant Water or Pools
Please be advised that the City of Grand Prairie treats swimming pools with larviciding agents only to prevent mosquito breeding and reduce the mosquito population; however, this treatment does not change the appearance of the swimming pool water, nor does it affect the pool chemicals already present.
Click here to report a stagnant pool or other mosquito issue.
Mosquitoes and Public Health
Mosquitoes can spread disease only when they bite their victim. Although it is commonly called a "bite," the process is actually a piercing-sucking action. Only the female mosquito bites, and takes a blood meal. The blood protein is needed to complete the mosquito's egg production cycle. During the feeding process, the female pierces her victims skin with her proboscis, (a long straw like structure with a sharp end) injects her saliva (which contains anti-coagulants) and then sucks the victim's bloods in through her proboscis. If the victim's blood contains disease-causing organisms, they too get sucked into the mosquitoes stomach. These organisms are then maintained within the mosquito and eventually may be injected into the next victim's bloodstream. In this way the mosquito can spread disease from animal to animal, animal to man, or even from person to person.
In the United States there are now about seven primary mosquito-borne viruses that are capable of crossing the blood-brain barrier in humans and other animals, causing an acute infection of the central nervous system. These include Western Equine Encephalitis, St. Louis Encephalitis, and West Nile Virus which have been known to occur in Texas.
Protect Yourself from Mosquitoes
Prevention of mosquito breeding and protection from bites is the best way to reduce your chances of being infected with mosquito-borne diseases such as West Nile Virus. Click here to learn more about West Nile Virus.
Mosquito season in this area is normally from about May through October. All citizens should do their part to aid in the abatement process and protect themselves observing the following guidelines:
- Dusk and dawn are the time of the day when mosquitoes are most active. Stay indoors if possible or limit outdoor activity during these periods.
- Use repellents that contain DEET as the active ingredient for treating exposed skin areas. Always carefully follow label directions. Click here for more info on repellents.
- Dress to keep skin covered as much as possible. Consider wearing loose, long sleeved shirts and long pants.
- Drain any standing water on your property. This includes any low areas where water may accumulate and items such as flower pots, cans, wheel barrows, boats, old tires, etc. that may hold water.
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How NOT to be a Yard Breeder
Remember, standing water means mosquitoes. Any standing, stagnant water that remains for 7 to 10 days after a rain can, and usually will, produce mosquitoes. For example, one coffee can full of water has been shown to produce in excess of 10,000 mosquitoes over an entire summer season
- Empty all water holding containers in your yard on a regular basis, at least once a week, children's wading pools, rain barrels, buckets, bird baths and stored boats are prime examples of mosquito breeding sites.
- Over-watering and poor irrigation practices are common producers of mosquitoes around the home, in parks and on golf courses. Report standing water to appropriate maintenance personnel.
- Clean out eaves troughs and down spouts of leaves and other debris that slows drainage.
- Maintain swimming pools circulation and filter systems, ph, and chlorine levels.
- Clean and replace pet water containers and bird baths daily.
- Keep gambusia, a tiny native fish that eats mosquito larvae, in your backyard pond. Also known as mosquito fish, gambusia reproduces rapidly: A female gives birth to about 60 young within 16 to 28 days after mating. (Frogs can, in turn, keep the gambusia population under control.)
- Use battery-operated Water Wigglers in birdbaths since female mosquitoes won’t lay eggs in moving water.
- Toss Mosquito Dunks, containing Bti (Bacillus thuringiensis israelensis, a bacterium) in rain barrels and the basins of water features. You can also put a few small pieces of the dunks in flowerpot saucers, where irrigation water might collect.
- Cast Bti granules, also known as Mosquito Bits, under dense shrubbery where mosquitoes breed in wet soil. Suggestion: Distribute it in spring and reapply during summer.
- Ditches must be kept free of vegetation and other debris to promote rapid drainage, and pond edges should be kept clean of cattails and other aquatic vegetation. This is where mosquito larvae develop and mature. To reduce the number of adult mosquitoes in your yard:
- Keep your lawn mowed as short as is practical.
- Keep all ornamental shrubs and bushes trimmed and pruned to open them up to light and air flow. This will not only give mosquitoes one less place to hide, but will promote growth and vigor in the plant.
- Cut back as far as possible, all low, dense under-growth surrounding your yard. This is where mosquitoes go to hide during the day.
- Have large trees trimmed to allow sunlight to penetrate dark, damp areas.
- Repair any water leaks such as outdoor faucets or sprinkler systems.
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Mosquito Life Cycle
Mosquitoes are members of the fly group (Order Diptera) and go through four distinct stages of development. All mosquitoes start their life as an egg. Some species of mosquitoes lay their eggs directly on the surface of the water and others lay their eggs in the moist soil around flood water sites. Eggs will hatch in water and larvae emerge. All larvae must go through four stages of growth, called instars, in the water, often known as wigglers. the next stage is the resting, non-feeding stage called pupa. In this stage, the mosquito becomes an adult.
Mosquito pupae always live in water. Female adult mosquitoes will mate and then leave to find a suitable host to suck blood.
She uses the blood to help develop her eggs and then she lays the eggs to start the cycle all over.
- Mosquitoes are responsible for more human deaths than any other living creature. Worldwide, nearly 4 million people die each year from various mosquito-borne diseases. Click here to learn more about mosquitoes found in America and worldwide.
- All mosquitoes must have water to complete their life cycle.
- Mosquitoes do not develop in grass or shrubbery, although, flying adults frequently rest in these areas during daylight hours.
- Only the female mosquito bites to obtain a blood meal. The male mosquito feeds only on plant juices.
- The female mosquito may live as long as three weeks during the summer or many months over the winter in order to lay her eggs the following spring.
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