Finding and Fighting Invasive Mosquitoes in Fullerton

Opening my bedroom window on a sweltering summer day, I noticed that a mosquito had climbed through a tiny hole in the screen. After using a spray bottle with rubbing alcohol to kill the small insect, I thought it was time to write about the OC Mosquito and Vector Control District. Based in Garden Grove, its primary objective is to protect the people of Orange County from the dangers of vector-borne disease. Connecting with Lora Young, the district’s Director of Communications, I was able to schedule a ride-along and interview with Senior Inspector III, Jerry Sims, who took me to a couple of sites in Fullerton to show me the different areas where mosquitoes like to breed.


Senior Inspector III, Jerry Sims, searches through stagnant water for mosquitoes.

Of the 3,500 species of mosquitoes worldwide, 53 occur in California, 23 in Orange County. These blood feeders have four stages in their life cycles. The first three stages are aquatic. The female mosquito lays eggs on or near a water surface; the eggs hatch a few hours or days later and the larvae emerge and feed on aquatic algae and bacteria. As they mature, they outgrow their skin, grow a new skin layer, and shed the old one through a process called molting. A few days later, the adult emerges from the pupal case and flies away. “The best way to control mosquitoes is to target their aquatic stages and the easiest way to do this is to deny them the water they need to develop,” said Inspector Sims. “Anything that will hold as little as 1/4 inch of water can support mosquito reproduction and should be emptied or drained.”

Before embarking on our search for mosquito breeding areas, Inspector Sims said, “Since about 2015 in Orange County, we’ve had a recent development with two new exotic species: one’s called the yellow fever mosquito and one is called the Asian Tiger mosquito. They’re both Aedes species and it’s something new. They are truly exotic and have different habits. At this point, the risk of disease transmission from them is low, but we’re getting a lot of calls just because they are so aggressive. It’s becoming a severe nuisance and at the very least, it’s going to impact the way people enjoy the outdoors. It’s only a matter of time before we have a local transmission cycle. These Aedes love small sources, including plants such as bromeliads, that collect a little bit of water in the crown of the plant, as well as the small saucers underneath. In an Aedes infested area, we typically find them breeding in exactly that environment.”


The OC Mosquito and Vector Control District works hard to eliminate existing mosquito breeding sources and prevent new ones.

Driving to the abandoned train tracks that run along Domingo Road in north Fullerton, Inspector Sims said, “It’s a good year for our normal mosquitoes, which transmit West Nile. We’ve only had one human case of West Nile in the county this year, which is extremely low. Although the mosquito abundance is high, we’re kind of at a loss at why the virus level is so low. But we have just a remarkable amount of mosquitoes out there since everything is so hot.”

Stepping out of the OC Mosquito and Vector Control vehicle, with its sticker reading, “Danger – Poison Storage Area,” Inspector Sims put on a pair of turquoise Latex gloves, and grabbed a bottle of highly refined mineral oil, which he uses to spray on the surface of stagnant water. The oil creates a thin layer that actually suffocates the mosquito larvae and quickly evaporates off the surface of the water. He also uses large white tablets called bacterial briquettes, which are very safe and targeted to mosquitoes. Sims said, “We can put these into a source and slowly release and get three-month control with these.”

Hiking down a small slope, Inspector Sims pointed me to an off-street drain flowing into a ditch filled with water on the side of the abandoned railway. “In the past, we’ve planted mosquito fish,” said Sims. “They are just a wonderful tool for us as long as they are not killed off by toxic pollutants or anything like that. They will live in a source and just effectively eat each mosquito larvae. The fish will maintain mosquito control within the deeper body of water. In fact, one fish is capable of eating over 100 mosquito larvae per day, but we still check it to make sure they’re still alive. They tend to be prolific even in stagnant environments because they’ll breed readily.”

At another old drain further down the tracks, there was a pool of dirty irrigation water that could potentially produce thousands of mosquitoes a week. Inspector Sims actually found some first stage larvae that were just barely big enough to see, so he treated it by putting in two tablets. “Sometimes as the water spreads out, you get these smaller pockets where the fish won’t be able to reach,” said Sims. “The smaller pockets toward the end of the drainage sometimes breed mosquitoes. Even in these drought conditions, water will drain off properties and slowly move through these systems. Unfortunately, it’s slow enough to breed mosquitoes and it doesn’t really have a push to clean out these systems in a proper way, like a good rain would do. With drought conditions, mosquito control is really a challenge.”



Following Inspector Sims down into a ditch with more drainage, I noticed that the water was barely moving. He said, “In these old systems, you start getting aquatic vegetation that will spread out and create dams that trap the water.” Luckily, there were no mosquitoes. But even if there were, I had protected myself with a Natrapel insect repellent, which was administered with a wet wipe. Further down, Inspector Sims found second-stage larvae in the water by using a long-handled scoop. Treading through deeper, dirty water, we came across some fourth stage larvae, which I saw squirming around in a small sample Sims had picked up. He treated this section with a granular form of the briquettes he was using earlier, which was easier to get into small pockets where there was a lot of dense vegetation. “This would be the product of choice for congested systems,” said Sims.

Once he was finished treating the ditch, Inspector Sims used an I-pad based system to find an address and make a house call, where a Fullerton resident had reported having mosquitoes. About one half of the mosquitoes produced in Orange County are found in residential backyards. Stepping into the resident’s backyard, Inspector Sims searched an out of service swimming pool, and plastic kiddie pool. “Remember, it only takes a week of standing water to produce mosquitoes, so do not allow water to accumulate,” said Sims. “We’ll do our part to look for sources, treat when necessary, come out to your home and give you some guidance, but it’s ultimately up to the homeowner to take a look at their yard. It really is a shared responsibility for you as the homeowner to become involved, talk to their neighbors about mosquito issues, and just become an advocate for the community to keep an eye out for potential sources. We’ll do our part and hopefully, the homeowner will do theirs.”



Fullerton residents can protect themselves from mosquitoes by wearing proven repellents, such as DEET, Picaridin, or Oil of lemon eucalyptus. It also helps to make sure window screens are in good condition and properly installed, while policing yards to look for potential sources. We can stay mosquito free by removing or drilling holes on the bottom of all plant pots, saucers, barrels, bins, and old tires. Do not keep water in buckets or root plant cuttings in water and remember to cover trashcans, toys and recycle bins. If you are bothered by mosquitoes, a Certified Vector Control Technician will investigate and lend assistance. If you have or are aware of an ornamental pond, unused swimming pool, or an animal drinking trough, the District will provide you with free mosquito fish. You can call the Orange County Mosquito and Vector Control District at (714) 971-2421 or (949) 654-2421 for more info.

To see my full interview and ride along with Inspector Sims, visit the Observer’s website, click on the “Videos” tab and click on the words “Emerson Little YouTube Channel,” which will take you directly to my page.


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