The Norman Transcript

July 18, 2013

City vector control officer experienced in trapping mosquitoes

By Arianna Pickard
The Norman Transcript

NORMAN — Stephen Warren seeks out the little pests everyone else tries to avoid in the summer to ensure Norman residents can enjoy the season without irritating bites and West Nile Virus.

Warren is halfway through his second summer of working as the vector control officer for the city of Norman Parks and Recreation Department. It’s his job mid-March through September to make sure the city’s mosquito population is kept under control throughout the warmest and dampest months of the year.

Norman is unique to most surrounding cities and states in that while other cities wait for complaints before they start spraying for the pests or spray regardless of complaints, Norman’s mosquito population is monitored every day to determine whether a spray is needed. Warren monitors the number of mosquitoes in Norman by trapping and counting them.

Each trap resembles a lantern with a light at the top to attract the mosquitoes, which get caught in a fan and pushed down the trap into a small jar where they’re killed by a pesticide.

Warren makes his rounds to each of the 13 traps about every other day and collects the dead female mosquitoes — the biters — out of the jars and takes them to his office to count them. If he finds 50 female mosquitoes in one trap for three consecutive days, he’ll investigate the area around the trap and consider whether it’s worth spraying.

“There are areas that are worse than others — you can just about count on it,” said Bill Ulch, Norman superintendent of parks.

Several factors can make an area a prime breeding spot for mosquitoes — particularly moisture and heat.

Mosquitoes tend to multiply after weather like Monday and Tuesday’s, when rain cools temperatures down and then it quickly heats up again, making the air very humid, Warren said. Mosquitoes love humidity and moisture, so their favorite places to congregate are near standing water or in areas of high foliage that hold in the humidity.

The hardest time to avoid mosquitoes is obviously in the summer when it’s warm, but especially at the beginning and end of the season when it’s a little cooler and there’s more rainfall. They like it hot but not too hot.

“April through September, you can see a rise in those general time frames, and then when it hits July, you know it just dips down because, like last year, we got about a month of just over 100-degree weather,” Warren said.

When Warren’s not out collecting dead mosquitoes, he’s trying to prevent younger mosquitoes from developing by larviciding areas with standing water.

Larviciding keeps mosquito population low by killing the larvae before the mosquitoes become adults, he said. It’s also safer than spraying because the larvicide uses a bacteria specific to mosquitoes that won’t harm their environment.

But this summer has been remarkably tame for Norman, as far as mosquitoes go. Apparently they didn’t enjoy the tornadoes anymore than the rest of us.

“Since the tornado, we’ve had these tipsy-topsy levels to where when it does rain and you get a lot of wind and a lot of weather, the mosquitoes naturally don’t like that,” Warren said.

Oklahoma has not yet had any reported cases of West Nile Virus, but last year, the state didn’t get the worst from its mosquitoes until August. From August through October, 176 cases of West Nile Virus were confirmed and 12 people died from the virus.

West Nile Virus is most commonly transmitted to humans by mosquitoes, according to the Centers for Disease Control and Prevention. There are no medications or vaccines to treat or prevent infections, but it can be prevented by using insect repellent to avoid bites. About 1 in 5 people infected will develop symptoms, and less than 1 percent develop a serious, sometimes fatal illness.

“West Nile Virus is difficult to detect because you can mistake it for a common cold,” Warren said.

Often people won’t know they have the virus until 40 years later when their immune system weakens and the illness begins to take over their nervous systems, he said.

Warren received a bachelor’s degree in zoology biomedical science from the University of Oklahoma and hopes to go into the medical field, but first he’s going to protect the health of Norman residents one mosquito at a time.