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Understanding mosquito misting formulations

The universe of formulations that are suitable for use in misting systems is small, and they fall into two categories – “Conventional” formulations which must be registered with the U.S. EPA because of the ingredients they contain, and “Green” formulations which do not have to be registered with the EPA.

The formulations most commonly used in misting systems are “Conventional”:

  • The active ingredients are either natural pyrethrins or permethrin, which is a closely related synthetic.  They also contain a synergist, piperonyl butoxide, which makes them more effective than they would otherwise be.
  • These formulations are known as “adulticides” and are very effective in misting systems.  They work by killing adult flying insects on contact – in the air or in landscaping where they harbor.
  • In order to use a conventional formulation in an automated misting system, it must contain directions for misting on its label.  There are only a handful of formulations that contain that language.  Insecticides that state “Not for use in outdoor residential misting systems” may not be used under any circumstances.  See What concentrate should I use and where can I buy it?
  • These formulations have been designed for misting and are suitable in MistAway’s systems because 1) they are water-based and contain only trace amounts of hydrocarbons, 2) they have been engineered to disperse evenly throughout the batch tank or drum when diluted with water, and 3) they have been formulated to avoid or minimize plant burn.

There is increasing interest and use of “Green” formulations in misting systems:

  • Generally, the ingredients found in these formulations are essential oils from plants, like geraniol, lemongrass oil and wintergreen oil.  There are also green formulations that contain sodium lauryl sulfate as their primary ingredient.
  • We have received mixed reviews on the effectiveness of green formulations used in misting systems, and it is unclear whether they work by killing insects – as the conventional adulticides do – they act as a repellant.
  • Be aware that the formulations from essential oils tend to be very chemically aggressive to plastics.  This means the dilute mist containing these oils has the potential to damage plastic surfaces that it contacts, like lawn furniture and clear coat on a fiberglass boat.  Their use also significantly increases the potential for failure of the components in the misting system.  This is particularly true in the Gen 3 tankless unit, which handles the formulation in its concentrated form.
  • The formulations containing sodium lauryl sulfate are not as chemically aggressive as the essential oil formulations.

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