Insecticide Fogging Applications

March 2023 Issue:

By: Jeff Waggoner, ACE

Is your understanding of fogging a little, well, foggy? Don’t be ashamed. Most do not understand the difference between fogging and fumigation. This, despite my efforts to explain it in other articles and social posts.

We found a bug so we better fog. Hold on there Sherlock. What kind of “insect” is it? We in the business refer to our bugs as insects. So there is a lot of science that goes into how to best treat for insects. Not only that, but some “insecticide” (see what I did there?) applications just flat out don’t control certain species very well at all.

All facility foggings are NOT created equal. Why is that? Good question my young Padawans. Let’s unpack that a bit.

Least expensive + least impactful: Thermal fogging. Thermal fogging creates a very thick “smokey” fog with very little chemicals. A typical chemical type maybe 0.5-1% pyrethrin products. This is usually a cheaper application but may only be effective against flies, mosquitos, and moths. If that’s your goal, then great! The fog is produced when the chemical passes into a heat tube and is vaporized.  The final particulate size is around 0.5-10 microns. This small particulate is warm, causing it to rise and suspend for a long time. Good in that it may contact an insect that flies, but bad for a crawling insect.  You can cover a lot of volume with a thermal fogger in short order. 

Average: ULV or Cold Aerosol fogging. This fogging type is fairly typical in a facility and can get adequate control of a variety of target pests. Chemical selection is critical and should be selected based on the species. Typical chemicals for these foggers are 1-3% pyrethrin, esfenvalerate, IGR (Insect Growth Regulator), and even vapona (DDVP or dichlorvos) products. These foggers typically produce a 5-15 micron size droplet that suspends well, but may also “grease out” at points of application if applied too fast. Problems arise when you try to fog too much space with too few application points. This results in poor coverage.

High impact + high cost: Fixed or Remotely applied products. The cost of a fixed application system or one that runs lines throughout the plant and pushes chemicals through it to nozzles may be costly to install initially but may pay dividends for sites fogging multiple times per year. These systems are typically powered by compressed air or compressed gases like carbon dioxide. You can use a variety of products but may be limited by manufacturer’s specifications. Maintenance is important to keep nozzles in good condition and clean. Remote systems are removable and can apply products from outside the target structure. This is a recent change to some vapona products as of October 28, 2022. I highly recommend you check your vapona product labeling for any changes in the application process before you use it in a traditional manner. Most of these applications are going to be more costly, but if they are properly designed to meet your unique needs, they may be the best bang for your buck when it comes to safety, compliance, and efficacy.

If you have been struggling to understand the difference in your quotations for fogging applications and something doesn’t look right, it probably isn’t the same application type. It may not even be working.  I’ve seen where someone might be using the wrong application AND the wrong chemical to treat a challenging target insect. That’s just wasting your time and money. Fogging is a great tool when used properly.  Just like any other pesticide application, it is important to seek the help of a knowledgeable professional. In most cases, it is just because the technician didn’t know.  You shouldn’t have to pay for their education. Contact those that know. If you would like to learn more about what a prescribed application might look like for your facility, please visit and get in touch with your local professional today.