ORANGE COUNTY MOSQUITO CONTROL INFORMATION

The following is designed to provide basic information and answer some of the most frequently asked questions about our operation.  If you have any additional questions, please call our office between 8:00 a.m. and 5:00 p.m. on weekdays at 883-5717 or 1-888-882-3621.

Surveillance

Surveillance tells us what types of mosquitoes are present and which parts of the county have the worst mosquito problem at any given time.  This information is the main basis for scheduling our control efforts.  There is no “routine” schedule for spraying. 

We have 16 mosquito traps located in Orange County.  The trapped mosquitoes are collected every morning, identified to species, and the number of each species recorded.  We also try to find “hot spots” by going to areas where we have numerous service requests and taking landing rates.  This is simply counting the number of mosquitoes that land on you in one minute.

Adulticiding

Adulticiding is the spraying of insecticides to kill adult mosquitoes.  Malathion is the insecticide that we use.  We have 8 spray trucks and it takes one week to spray the entire county working Monday through Thursday nights.  When mosquito activity levels are high we also spray Sunday nights.  It is useless to spray during the heat of the day because the sun causes hot air to rise from the ground.  Our spray is caught in this air current, goes up instead of drifting through and across yards, and does not kill the mosquitoes.

Mosquito control insecticides have no residual action and kill only the mosquitoes that are hit by a spray droplet.  If more mosquitoes fly into an area after the spray has settled, then they are not affected and it appears as though the spray did not work.  This is often the case when mosquito populations are high.  We try to retreat these areas as soon as possible.

When you see a Mosquito Control truck spraying in your area, please do not remain outdoors.  The drivers have been instructed to discontinue spraying in areas where people are present to prevent exposure to insecticide.

For safety reasons, the drivers spray only on the way out on dead end roads.  This prevents them from driving through the spray.

Our drivers are instructed to drive 15 m.p.h. when actually spraying insecticide to comply with the E.P.A. label regulations for malathion.  It will sometimes appear that they are going faster than that when the observer is standing still watching the vehicle pass by, but remember that 15 m.p.h. is ¼ mile per minute, the equivalent of running a mile every four minutes.

Because of our 15 m.p.h. spraying speed limit, it is unsafe for our drivers to spray roads with a speed limit in excess of 40 m.p.h. or roads that have a heavy traffic load.  We have also been advised not to spray private property and driveways due to insurance and manpower problems. 

Larviciding

Larviciding is the application of chemicals to water to kill immature mosquitoes.  The idea is to kill the mosquitoes before they can bite or reproduce, and this work is done during the day, Monday through Friday.  We have 2 larviciding vehicles and it can take as long as 4 ½ weeks to treat the entire county.

Our larviciding program is directed toward roadside ditches and storm drains that produce the mosquito that can transmit St. Louis Enchephalitis.  Because most of these ditches are in front of houses where children and pets play, we do not use insecticide in the water.  Instead, we apply an E.P.A. approved light oil film to the surface to suffocate the larval mosquitoes.  We ask the public to help by getting rid of standing water in containers and low areas whenever possible.