Spray Truck Q & A

SprayTruck app TA

Spray trucks are only part of our overall control program and are the part the public most commonly recognizes.  Below is a list of some of the most commonly asked questions and answers. 

Do trucks come on a schedule? 

Adulticide treatments are determined on a day-to-day basis when surveillance has indicated that mosquito levels justify the need for spraying and is in accordance with state rules and regulations. The District uses a network of mosquito traps to catch and quantify flying mosquitoes to determine if treatment is warranted. 

If you are growing your own mosquito larvae in containers around your house, a spray truck is not going to help. Check around your house and property looking for containers, natural or manmade that may hold water.  Refer to the Homeowner Tips page for areas to check and to the Home-Grown Mosquitoes video to be able to recognize what mosquito larvae look like.

What does “ULV” mean?

It means “Ultra-Low-Volume”.  Specialized spray equipment creates a fine mist of droplets that are released to drfit through the targeted zone.  The droplets persist in the air for a small amount of time at a density to contact the flying mosquito.  It is only effective while the droplets are in the air and therefore has no residual effect.


What pesticides do you use, how much and do they harm people or pets?

Our spray trucks currently use a formulation of permethrin, a synthetic pyrethroid. Permethrin is the ingredient in many household insect sprays and is even used in some lice treatments intended to be applied directly to children. As we are only spraying for flying adult mosquitoes we only need to create a fine mist that will stay in the air. As such we can get the job done with a very small amount of chemical, typically we apply only about one half to three quarter tablespoons per football field sized areaThe tiny amounts we use are not harmful to common pets.

The volume of spray is computer-controlled so we apply the same amount per mile no matter how fast the truck is driving. The idea that you get more spray if the truck is driving very slowly is incorrect. The federal pesticide label dictates the maximum amount that can be applied per-acre, so computer control is necessary to make sure we do not exceed that amount regardless of truck speed. 


Why do you only spray at night?

The adulticide spray is not a preventative measure. The spray must come in contact with mosquitoes that are actively flying and should be done at the time they are most active, which is usually in the evening. Ideal conditions for spraying are a warm, low, steady, wind from dusk onward. Mosquitoes are typically low to the ground, hiding in moist vegetation. During the daytime, sunlight striking the ground causes thermal air currents that tend to make our sprays just rise straight up into the air.  Also during the day there are many beneficial insects which are active, especially bees, and we don’t want to harm them with our spray. 


Why don’t you spray the ditches behind my house?

Because of the tremendous human resources required to inspect and treat mosquito larvae, we restrict our larval control efforts to the two species of salt marsh mosquito which are produced primarily east of US 1.  It is imperative to stop these mosquitoes at the larval stage because, as adults, they are incredibly prolific, pestiferous and capable of flying up to 25 miles.


The mosquitoes are covering my walls.  Why aren’t you spraying them ?

If something that looks like mosquitoes are "covering your walls" then they are not mosquitoes at all. These are aquatic midges, which are often callled "blind mosquitoes". The larvae grow in the mud along the margins of ponds, even golf "water traps" and generally emerge as adults en-masse once or twice a year. They seem attracted to bright surfaces. They do not bite nor do they transmit any diseases. Typically they die off in just a few days. Refer to the IFAS Fact Sheet on Blind Mosquitoes to learn more.


Do you spray for no-see-ums?

No. We do not provide control for biting midges, "blind mosquitoes" or no-see-ums. Our mosquito adulticides and equipment are not very effective against no-see-ums.


How far does the spray reach?

In the 1980’s the IRMCD conducted extensive field tests to answer that question, using a large variety of spray rates and equipment modifications under varying weather conditions. The spray droplets do eventually evaporate, dissipate or settle so they become less effective with distance. Our research revealed that, as a rule of thumb, adequate effectiveness extends to about 300 feet downwind from the truck. This is why, in some neighborhoods and mobile-home parks, where roads are very closely spaced, we might drive only every other street. It is also why in “country” areas where roads are very far apart that we cannot achieve the same level of mosquito control as elsewhere.

Why didn't I see you spray?

This is a very common question and there can be many answers :


1) Weather - If it raining or wind conditions are not suitable, then the treament is postponed. 

2) Border of Spray Zone - We divided the county into more than 60+ “spray zones” that each take about two hours to spray. If you hear the truck but never see it, you may actually be near the border of a spray zone and the truck was spraying an adjacent zone. Refer to the Spray Zone Map to determine your zone number.

3) Driver Error - While we now have GPS guidance in our trucks, drivers are still human and can sometimes take a wrong turn in the dark.

4) Mechanical issues  - Trucks can break down and not finish a route. We will usually re-schedule the unfinished portion of a route for the next evening.

5) Unsafe Road Conditions - Sometimes there are obstructions or road conditions might be so bad that the driver opts to skip an area. Heavy rains can so severely flood some areas that, at night, you literally cannot tell where a road ends and a deep canal begins. We resume spraying when conditions improve.

6) Wrong Gate Code or Locked Gates - Gated neighborhoods don’t always keep us informed if they change the gate code. Likewise, some rural properties may have padlocked gates.  We maintain a "Gate-Call" list to notify the property owners before we spray the area, reminding them to leave gates open so we can get in. Our drivers do not open gates themselves for legal and safety reasons. Contact us to be put on the “Gate-Call List”.

7) Loose Dogs - Do you have dogs that run loose? We may opt to skip properties where there’s a risk of running-down free-roving pets. Typically we will make an attempt to contact such property owners about the problem.

8) Location - Your street may be covered by being within 300 feet of spray on the adjacent street

9) Vegetation Coverage - Your street may be covered by thick vegetation preventing access for spray truck.



For safety reasons we encourage our drivers to NOT stop and talk to anyone. If you need to contact us, please call our office at 772-562-2393 or send an e-mail to: irmcd@irmosquito2.org