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Mosquito Spraying: A Guide to Different Application Methods for Communities and Yards

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Mosquito control services use a variety of different application methods to control mosquitoes in communities, private backyards, public parks, and commercial properties. There is no one size fits all solution for keeping mosquito populations in check. Mosquito management programs improve quality of life and comfort when spending outdoors, but are most important for limiting transmission of mosquito-borne diseases such as West Nile Virus, Zika, and various types of Encephalitis.

If you’re a resident of a community that provides mosquito control treatments, or you are looking to hire a service to reduce mosquito populations on your own property, it will be helpful to know the 3 main types of control methods used, along with the benefits and drawbacks of each.

Three Types of Mosquito Spraying:  Night-Time ULV Treatments, Barrier Applications, and Larviciding

There are three types of mosquito control applications that are the most commonly used to reduce mosquito populations:

  1. Night-time Spray Treatments
  2. Day-time Barrier Applications
  3. Wide-Area Larvicide Applications

How do Night-Time Mosquito Spray Treatments work?

dusk time msoquito spray treatment with electric ULV machineNight-time mosquito control applications are commonly used for wide-area mosquito control, such as across an entire community or a very large commercial or private property. Night-time mosquito control treatments are conducted using Ultra-Low Volume (ULV) application equipment, typically mounted to the bed of a pick-up truck or an ATV. In some regions, fixed-wing aircraft are used to make night-time mosquito treatments in order to cover a large geographic area in a short window of time. Both the EPA and CDC recognize a legitimate and compelling need for the prudent use of night-time spray treatments to control adult mosquitoes, especially to prevent the risk of mosquito-borne disease.

ULV equipment converts a liquid mosquito control product into an ultra-fine spray cloud comprised of microscopic droplets that are so small, more than 15 individual droplets could fit on the head of a pin.  The small size of the droplets allows them to float through the air for a short period of time so they can come in contact with flying adult mosquitoes. The droplet formulation is designed to penetrate the cuticle of the mosquito, affecting its nervous system, knocking it down and ultimately delivering mortality. ULV applications for mosquito control use a very small amount of product and a very low amount of active ingredient. Mosquito control formulations use often contain less than 2% active ingredient, and applications put out 1 ounce of formulated product per land acre (about the size of a football field). The dose is extremely low because it is formulated to work specifically on mosquitoes.

The Benefits of Night-Time Mosquito Spraying

The benefits of night-time mosquito spraying include:

  • Applications are done after dusk or at dawn when mosquitoes are most active.
  • Quickly and effectively reduce active mosquito populations to improve quality of life and prevent disease transmission.
  • Sensitive insects like honey bees and butterflies are usually sheltered or not active when night-time mosquito spraying occurs, limiting the exposure risk.
  • Very low dose rates are required for mosquito control.
  • All products used are EPA registered for residential and wide-area public health mosquito control, and go through thorough efficacy and environmental impact studies before being registered for use.

The trade-offs for night-time mosquito spraying include:

  • Only effective on mosquitoes flying and active at the time of treatment – will not fully eliminate mosquito populations.
  • Relief is temporary. Sprays will dissipate quickly through the treatment area (in 5-30 minutes, depending on weather conditions). They do not have any residual effect.
  • Overnight application timing can leave residents wondering if they were actually treated.

How do Mosquito Barrier Sprays Work?

Mosquito barrier spraying with a backback Comparatively, there is another type of mosquito control treatment conducted during the day called a barrier application. Barrier treatments are the most common application method used for backyard mosquito control. Many barrier products do contain the same active ingredients that are used for night-time spray treatments, but the dose rate and application method, and in some cases even the formulation design, are completely different.

Mosquito control products formulated for barrier control are designed to last in the treatment area for several days, if not weeks, depending on the product used and weather conditions. They work by controlling mosquitoes that land and rest on treated plants or hard surfaces. And because the product works on contact and needs to last for an extended period of time in a wide range of weather conditions, the dose rate required for mosquito control is much greater than what is used for night-time ULV applications.

When it comes to barrier applications, they are conducted using backpack spray systems that convert the liquid product into large droplets – 3 to 10x larger than a ULV droplet. The product is applied to vegetation (landscaped plants, foliage, tree lines, etc.) where adult mosquitoes like to rest during the daytime hours. Depending on the product used and the type of license the applicator holds, these products can also be used on hard surfaces around your property like foundation walls or fences. However, barrier products should not be applied on lawns, gardens, or any flowering plants.

The Benefits of Barrier Spraying for Mosquito Control

The benefits of barrier treatments on vegetation for mosquito control include:

  • Targets the specific areas where mosquitoes rest during the day.
  • Slowly reduces and helps maintain low mosquito populations in the treatment area for several days or weeks.
  • Applications are done during the day, providing treatment confirmation to property owners who are home at the time of treatment.

rain drops on vegetation

The trade-offs for barrier spraying for mosquitoes include:

  • Highly susceptible to weather conditions – heavy rain following a barrier application could decrease the length of control.
  • Applications on plants may unintentionally expose other insects that rest or feed on treated vegetation.
  • Some, but not all, products used for barrier control are EPA-registered and required to demonstrate lasting efficacy on mosquitoes. Many “natural” mosquito products are not registered with the EPA and in many cases, require no scientific proof they work!

What is Wide Area Larviciding?

Larvicides are mosquito control products that control mosquito populations in the larval stage of their life cycle. They are applied directly to the water sources where adult female mosquitoes lay their eggs, and work to prevent mosquito larvae from ever becoming flying, biting adults. Larvicides come in many formulation types, including liquid, granular, and tablet forms to name a few, and can be applied through a wide range of equipment, including by hand, backpack blower, a helicopter or airplane, or air blast equipment.

Buffalo Turbine air blast equipment applying larvicideAn emerging method for applying liquid larvicides over a wide area uses a turbine-powered air blast Wide area liquid larviciding with air blast equipment was first introduced for mosquito control during the Zika outbreaks of 2016 and 2017 in Miami-Dade County and Brownsville, Texas. These communities needed an alternative to applying liquid larvicide by air over urban communities that could still efficiently reach backyards and other obstructed areas where mosquito breeding was occurring.

Wide area liquid larvicide applications differ from wide-area night-time ULV treatments in a few key ways, including:

  • Airblast equipment such as the Buffalo Turbine put the product out through ULV nozzles, directing droplets up, 80 – 100 feet into the air. This allows the droplets to move through the air, up and over buildings, tree lines, or other obstructions, before ultimately depositing into cryptic water-holding objects and places where mosquitoes lay buffalo turbine air blast applications work
  • The droplet size required for wide-area larviciding through an air blast machine is greater than what is desired for night-time ULV applications, but still much smaller than used for a barrier application.
  • Larvicide treatments have a wide, flexible treatment window – they can be scheduled for any time of day that works best for the community.

Keep Diving into More Mosquito Control Information:

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More Questions about Mosquito Spray Treatments?

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