What Chemicals Do Mosquito Spray Trucks Use?

This is one of the most commonly asked questions whenever somebody hears that a mosquito spraying will be happening in their neighborhood. Since these sprayings are becoming a more common thing with all the Zika virus, West Nile fever, and dengue fever threats floating around, I thought it would be beneficial for us to find out what exactly the mosquito trucks are spraying and how it can affect us.

What do the sprayings target?

Usually, both larvicides and pesticides are used when mosquito spraying happens in any area. This strategy is employed not only to get rid of all the adult mosquitoes in the area so that there is less of a chance that you will be bitten by a mosquito but also to get rid of mosquito larvae so there are no mosquitoes waiting to mature and cause more problems.

The sprayings take place at night as that is not only the time when the least amount of people and beneficial insects are on the streets but also because it is the time when the mosquitoes are the most active therefore the most mosquitoes can be targeted.

What chemicals are actually used by the mosquito trucks?

One of the chemicals that is most commonly used in the ground foggings or those done from a car or on foot is Zenivex. This is an effective pesticide that targets adult mosquitoes. For that reason, it usually is used in conjunction with a larvicide. It is an oil-based fogging solution that can be used in both urban and rural areas since it is approved for use even on agricultural crops. The main active ingredient in Zenivex is etofenprox, an adulticide, which is an insecticide that targets adult insects by disturbing their nervous system when they come in contact with the chemical, eventually causing death. Luckily, etofenprox insecticides and, therefore, by default also Zenivex, have a low toxicity for birds. When the spray has dried, it becomes harmless to living creatures like bees and dogs as well.


Mosquito spraying programs also use permethrin-based solutions, which is another insecticide that is long-lasting and efficient. Once dry, it does not kill beneficial insects like bees and does not harm humans and pets either.

What should you do when spraying is scheduled?

All of these solutions, whether a permethrin-based one, Zenivex, or an entirely different insecticide are distributed with the help of an ultra-low volume (ULV) fogger which is able to turn the liquid solution into a very fine fog, allowing the insecticide solution to penetrate into all of the small cracks where mosquitoes tend to hide.

Of course, any insecticide is still a chemical, so if you want to be completely sure that you are not breathing it in and that your pets or other things will not suffer, then I would suggest that you close your windows and doors when the spraying is scheduled. You should also keep your pets indoors and cover your beehives and fish ponds so they do not come into contact with the freshly sprayed insecticide.

But, people really shouldn’t be that concerned about mosquito spraying because not only are these insecticides approved by institutions such as the US Environmental Protection Agency but also because the volume of insecticide used is actually very small. In the end, it is a chemical exposure that is about 10 times weaker than you would experience if you used a flea shampoo on your dog. And, of course, the mosquito spray is much less harmful than what a mosquito could do to you if it were to bite you and infect you with a disease. So, even though some may worry that these sprayings are harmful, the truth is that they only affect our lives in a positive way.


Main editor

Expert in mosquito control and the main website editor at InsectCop.net. Karen started InsectCop to help people get rid of mosquitoes. But now she gives advice an all things pest control.


Greta Garbo

My brother & I used to walk behind the mosquito trucks in the 70’s whenever they sprayed. We are. Oth in poor health. I was wondering if this was related to the chemicals in the fog that they sprayed. We thought it was fun to walk into it & did it way to many times. Are we paying the consequences now? I’m 61 & my brother is 58.


    It depends on what was used to kill the mosquitoes. If malathion or an organophosphate were used, which at that time were the more popular mosquito fogging chemical options, then running behind the mosquito truck as a kid shouldn’t be the cause for your poor health. Many think that DDT (which was banned in 1972 but actually isn’t even toxic to humans) was used as the fogging chemical and because of that associate mosquito trucks with poor health. But since DDT is a larvacide it wasn’t used in the fogging trucks, it was mainly put into the water to control mosquito larvae.


    YES!!! Roundup would have come out around the time you and your brother were kids being kids. We all liked doing things that seemed innocent but the after affects have proved to be deadly later in life. Learn about it and get tested for acetylcholinesterase aka Roundup toxins. This article is very eye opening.


    Roundup is for vegetation


was just at a party where we ‘kids’ realized nearly ALL of the moms on the main mosquito truck route (1960s) have had breast cancer. kinda wishing someone would do a map/correlation. we’re assuming the new stuff is safe, of course… then again, our folks were told it was safe back then. (?)

just as important (maybe, more) is the new standing water in our village — the result of inappropriate building (marshes and low level ponds where there’s used to be grass, stagnant puddles where there used to be a flowing creek). in the last few weeks, they’ve dug trenches that don’t drain to culverts. with our heavy clay soil, these puddles simply aren’t draining (or even evaporating in 98 degree full sun).


    Go to CDC.gov and search for epidemiology section. You might have to call them, but epi is set up for this purpose. Blessings.


Our city truck has been fogging people’s backyards which go right by our vegetable garden, chickens, meat rabbits and honey bees – just feet away. I can’t imagine that this isn’t toxic to them, their water, their air and eventually, to us. Comments?


    It depends on what chemicals are being sprayed. I’d suggest you contact your local vector control district or government department and ask them what type of insecticide they use in your area.

Debbie D

In the town I live in.. I have had numerous trees and plants die after the town began their fogging. What can i do about this? It’s very frustrating planting plant and nice bushes and then all of a sudden the blooms dry up and fall off the flowering rose of sharon. And I had a white peach tree and tree was a young beautiful tree. Health and was just beginning to produce fruit. Then the fruit dried up and the leaves fell off and the tree died. All in a month. This is getting expensive and aggravating to say the least! And trying to get answers is like getting straight answers from a politition!


    This sounds awful! Unfortunately, I don’t think there’s much else you can do, other than talking to the officials. Have you also talked to your neighbors? Are they experiencing the same effects? Good luck figuring this out!


All the kids in my neighborhood ran behind the fog truck in the 60’s. We were told that the fog was vaporized no. 2 fuel oil. is that true ?


    Unfortunately, I don’t have much knowledge on what chemicals were used back then.

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