Mosquito ‘Sewer Monster’ fights the biters in Chicago’s north suburbs

Justin Harbison lowers a long stick with a cup into a stormwater catchbasin to scoop up a sample of sewer water.

He lifts what he calls his “dipper,” then uses a finger to sift through the murky water.

“I see some larvae swimming around,” he says.

Harbison, a Loyola University Chicago researcher and self-described “Sewer Monster,” hopes that a chemical treatment placed in the sewer in June will kill the newly hatched mosquitoes, keeping them from growing into adult biters.

The insects that everyone hates aren’t just annoying. In Illinois, they can spread the potentially deadly West Nile virus, an illness that sickens thousands of people across the country every year. There have been no human cases reported in Chicago this year, but health officials expect that might change.

Harbison, who wears his “Sewer Monster” nickname on his shirt, is passionate about protecting public health.

Maybe it was destiny. As a kid in the 1980s, when “Ghostbusters” was a hit movie, he dressed up instead as a “bug buster.”

“I was also kind of the kid who always liked to gross out people,” he says. “When I first got into sewer work, I kind of loved it because no one else was doing it. It’s kind of gross.”

Harbison helps advise a team of experts in Northfield, one of four mosquito-abatement districts in the Cook County suburbs, working to control populations by adding insecticides to water where mosquito larvae thrive. After feeding on blood, females need water to lay their eggs during warm weather months. So the sewers are an ideal place for mosquitoes to lay eggs. They are active usually from June to early October, though they’ve shown up as early as May.

West Nile virus is what worries public health officials these days, though historically other serious illnesses also have been transmitted by mosquitoes.

Across Chicago, which contracts with a private company to control mosquitoes, chemicals attacking larvae and preventing them from developing are also added to sewers.

These sewer mosquitoes can lay 200 eggs at a time in water. Thes are the pests most likely to spread West Nile in cities.

The larvae munch on decaying leaves and other muck that fall into sewers through drain openings.

“Mosquito females know that it’s a really good spot to lay their eggs because they’re going to have lots of food there,” Harbison says.

By treating the sewers, Harbison estimates he can reduce mosquito populations by more than 35%.

Along the North Shore, where Harbison spends most of his time consulting, all 80,000 catch basins in Cook County’s north suburbs and parts of southern Lake County have chemicals placed in them.

The North Shore Mosquito Abatement District, the government agency that relies on Harbison’s help, says it has had no human cases of West Nile this year, last year or the year before. The district covers a 100-square-mile area where about 350,000 people live.

Most mosquitoes just a ‘nuisance’

In Chicago, similar larvicide treatment is done in 80 sewer sites out of about 210. That number fluctuates year to year, depending on what mosquito surveillance shows, as well as funding available, according to a city spokesperson.

If larvicide sounds scary, consider that it reduces the need to spray pesticides. It also beats using dynamite to reduce ponds of standing water where mosquitoes breed, a practice used for almost half a century that largely ended by 1970.

“Our techniques improved greatly. We’ve moved away from dynamite,” Harbison says, explaining that larvicide used at low levels isn’t harmful for humans and animals.

Spraying pesticides can harm pollinators like bees and butterflies that are beneficial to gardens and the environment, though government spray trucks usually go out at night, when mosquitoes are active.

Chicago sprays when tests show an area has a concentration of mosquitoes infected with West Nile virus, according to Dr. Janna Kerins, a city Department of Public Health medical director.

“The vast majority of mosquitoes are nuisance mosquitoes, but, that being said, West Nile virus is something that does occur in Chicago,” says Kerins, who focuses on controlling the spread of the virus. “It’s important that people know they should be protecting themselves.”

Last year in Chicago, there were 34 cases, including two deaths. Infected mosquitoes appear in every neighborhood, though there generally are fewer mosquitoes closer to Lake Michigan, Kerins says.

Last year required additional protections against the virus-carrying insects. In addition to using the larvicide, the city sprayed pesticides seven times in more than a dozen communities in July and August. Some years, there’s no need to spray, something that’s attributed to the sewer treatments.

For some, the virus can be lethal. People over 65 years old or anyone with a compromised immune system, including those with diabetes or cancer, are most at risk.

Your chances of getting West Nile are actually low. Four of five people infected show no symptoms. There were 82 known human cases in Cook County last year, though that likely undercounts the actual number. Some people might not even realize they have the virus. The effects can range from mild flu-like symptoms to serious brain swelling caused by encephalitis.

When the virus was first detected in humans in Illinois two dozen years ago, it grew to be an epidemic, killing dozens of people and sickening hundreds more. Efforts to reduce the mosquito populations, educate people about the risks and fewer birds carrying the virus have resulted in reduced numbers, according to the Illinois Department of Public Health.

Keeping skeeters at bay

Harbison recommends that people use repellent with 30% of the chemical DEET or another government-registered ingredient, such as picaridin or lemon eucalyptus oil. You also can buy clothing that repels the pests or treat your clothes with the chemical permethrin.

Another way to help fight mosquitoes: After heavy rains, dump any standing water around a home or property. That includes flower pots, tires or anything else that can collect rainwater.

“If it can hold water, it can breed mosquitoes!” is the slogan at the North Shore mosquito-abatement district, Zazra says. Health officials also urge people to report standing water that can encourage breeding.

Mosquitoes instinctively know where water will collect, such as the saucer below an outdoor pot. More than one million years of evolution have informed them, according to Zazra.

“Mosquitoes have been around longer than humans, so they have a running start,” Harbison says.

Which makes it all the more important to get ahead of breeding season.

“Mosquitoes populations are going to grow exponentially,” Harbison says. “Any mosquito can become an adult. In theory, you’re eliminating 200 mosquitoes. And they can produce another 200. I may be eliminating transmission of a disease. It’s something that’s doing some good.”