Insect foggers can generally be categorized into two large groups:
You may have come across one or both of these terms when browsing for pest control products.
While the purpose of both types of fogger is the same, they use different fogging techniques and require different types of fogging liquids. And when talking about cold foggers you can make the decision to buy a handheld fogger or more practical backpack fogger.
Thermal foggers are so named because they heat up a coil within a metal tube, causing the liquid insecticide solution to vaporize. They then propel this vapor (composed of hundreds of tiny droplets) out in a visible cloud. The heat for thermal foggers comes from either propane or electricity.
As mentioned, there are two types of thermal foggers:
- Gas thermal foggers – require a gas cylinder (usually propane) to be mounted to the fogger.
- Electric thermal foggers – use electricity or batteries.
Gas and battery-powered foggers are cordless, fully portable, and can be used anywhere, while some electric foggers are subject to the length of their cable or an extension cord.
Propane foggers are more expensive due to the consumption of gas instead of electricity.
ULV (ultra-low volume) foggers, also called cold foggers, don’t use heat. Instead, they produce fog using pressure in one of two ways:
- Either the insecticide solution is pumped through a high-pressure nozzle
- or the solution is slowly sent through a vortex of high-speed air. The pressure breaks up the liquid into tiny droplets, which then spray out as an invisible fog.
The motors are typically powered by either electricity or batteries but some models use gasoline. Operators can adjust the size of the droplets produced by ULV foggers, allowing for different uses. The lack of heat (and thus fire risk) makes ULV foggers safer for indoor use.
Droplet sizes vary by model.
- Thermal foggers generally produce smaller droplets, with a minimum diameter of 1 micrometer.
- ULV foggers typically produce slightly larger droplets, with a minimum diameter of 2 micrometers.
Because thermal foggers produce such small droplets and visible fog, they are ideal for outdoor applications. Smaller droplets hang in the air longer, increasing the likelihood that they will contact a flying insect.
Furthermore, tiny droplets penetrate dense foliage better than larger droplets. Visible fog is easier to monitor and control than invisible fog, allowing for greater efficiency.
However, because the droplet diameter cannot be controlled in thermal foggers, their size can vary dramatically, which somewhat reduces their efficacy.
ULV foggers, on the other hand, produce more precisely sized droplets that can be varied by the operator. This provides versatility not available in thermal foggers.
And, as their name suggests, ultra-low volume foggers use less insecticide, making them more economical and slightly more environmentally friendly.
Thermal and ULV foggers have similar uses in many aspects. Both can spray either a water or oil-based fogging solution
However, in some situations, one or the other type may be better suited.
Thermal foggers generate smaller droplets in a visible fog, making them ideal for such applications as:
- Insect control (including mosquitoes): For control of insect vectors (insects that transmit diseases/viruses to humans), the optimal droplet size is 10-15 micrometers, well within the range produced by thermal foggers. As mentioned, smaller droplets remain suspended longer and penetrate dense vegetation better than larger droplets.
- Directed outdoor applications: The visibility of the fog produced by thermal foggers allows for operators to monitor and control the direction of the spray.
- Small, hidden areas: The small droplets produced by thermal foggers are ideal for depositing insecticide in cracks and crevices in floors, ceilings, and walls, as well as dense thickets and other foliage.
ULV foggers, on the other hand, don’t heat up, reducing the risk of fire. Furthermore, the invisible fog makes them better suited for neighborhoods and military encampments, where visible “smoke” could cause alarm. They are also quieter than thermal foggers.
ULV foggers can be used:
- Indoors: As mentioned above, ULV foggers do not heat up and can be used inside.
- Disinfecting and odor control: ULV foggers can be used to disinfect indoor spaces and can be operated remotely.
- Mold and fungal control: Mold control solutions and fungicides can be applied using ULV foggers indoors as well as on crops (in greenhouses or gardens).