Still Water Brings Bugs to San Onofre Beach, but Experts Say Mosquito Counts Are Down

After an above-average rainy season, insects are out in full force.

Spring is here, and so are the bugs.

The increase in stagnant water around the creek-fed wetlands at San Onofre State Beach and other beach parks has provided breeding grounds for swarms of flying insects, including midges and possibly mosquitoes.

"Our trap counts are negative for mosquitoes in the area," said Jared Dever, Orange County Vector Control's director of communications. "[But] there are insects that are almost identical in body size and shape and have almost the exact same characteristics of a mosquito, but they're referred to as midges."

Midges often travel in groups and tend to fly above stagnant water, trees and/or shrubbery. They pose no threat in this area of California, said Dever.

"In agricultural settings, midges can, on rare instances, transmit disease with their legs by landing on different crops or animals," said Dever. "But that is incidental."

Because a midge does not have a proboscis, the needle-like body part that allows the insect to take blood and transmit disease, the Orange County Vector Control District does not consider the midge a vector.

"It's very common for people to identify midges as mosquitoes," said Dever. "[But] mosquitoes are almost always solitary, and they don't cluster in large groups."

Although stagnant water will breed mosquitoes, it will also breed midges. Mosquitoes only need stagnant water to lay their eggs on the surface; midge larvae require soft soil bases and muddy bottoms so they can burrow in the soil for a period of time, said Dever.

The estimated rainfall for Orange County has measured at above-average levels, 18 inches this year. The average level is about 12 inches a year.

"Just add water and you get a lot of plants, weeds and animals from all different trophic levels [different levels of the food chain]," said David Pryor, senior environmental scientist for the Orange Coast District, the agency that administers San Onofre State Beach and the other state parks in Orange County. "It's been an abundant year. I would expect to see a lot of life this year because of the above-average rainfall."

The West Nile virus, the most well-known virus transmitted by mosquitoes, was last reported in Orange County in 2005. With the increase in overall insect population this year, O.C. Vector Control has kept a close eye on all potential mosquito breeding grounds and treats each area with organically derived products.

"Some of the products are actually bacteri[a] that are found in the soil naturally," said Dever. "They're basically grown in a large factory, put onto corn cobs and kernels, which are ground up and are extremely target-specific."

When the mosquito larvae ingest the bacteria, it prevents the larvae from hatching. Each treatment is referred to as an "insect growth regulator" and can cause different side effects on the mosquito.

"They can prevent them from developing a wing correctly," said Dever, "so it won't actually harm the other insects."

Mosquitoes are attracted to carbon dioxide given off when an animal or a human exhales. These insects prove to have specific taste, depending on the individual mosquito's attraction to the subject's acidity levels in the skin, Dever said. Mosquitoes' blood-type preferences have been known to include those of frogs, birds and mammals, as well as individual humans. 

There are some who believe certain colors attract the insect, but the mosquito relies on smell and heat.

"Certain chemical sensors that your body is giving off lets the female mosquito know whether you are adequate for her or not," said Dever. "They're also able to see your body heat, kind of like a thermal vision."

The Environmental Protection Agency and the Centers for Disease Control recommend using insect repellents that are scientifically proven for their efficacy as well as longevity. Products containing the active ingredients DEET and picaridin have proved to offer longer lasting protect than other products.

As for all-natural options, Dever recommends eucalyptus oil and citronella candles. 

Read the full article at: https://patch.com/california/sanclemente/still-water-brings-bugs-to-san-onofre-beach-but-exper3a211ac1c2