News

May 11, 2023

Butte County Mosquito and Vector District braces for summer

OROVILLE — Each year, Independence Day brings on summer traditions like

OROVILLE — Each year, Independence Day brings on summer traditions like fireworks, cookouts, spending time under the blue sky and that faint buzzing sound of a small creature who is quite literally out for blood.

The Fourth of July, broadly speaking, marks the beginning of what the Butte County Mosquito and Vector District knows all too well as West Nile season. The weather has been consistently warm enough up to that point, for the virus to expand inside of birds to the point that mosquitos can easily contract it with a bite.

"It's right around Fourth of July," said Matthew Ball, the district manager for the Mosquito and Vector District. "Right when everybody's out doing fireworks, having barbeques and everything like that. We usually find our first positive mosquitos carrying West Nile right around the corner."

Ball has been with Butte County's vector control district since 2008, but West Nile has been in the county since 2004 and is considered endemic at this point, so he's been dealing with it directly throughout his time as manager.

The job of the district consists of, as the name implies, controlling mosquito populations, among other insects that pose a health risk, and keeping tabs on where the virus is being spread. The back room of the office is a lab with specimens, both dead and alive, to be identified through microscopes and tested for West Nile.

Ball said his department focuses on mosquitos, ticks and yellowjackets.

In the lab Wednesday morning, four bags full of buzzing mosquitos were hung up after being trapped in order to test. Ball said each bag contained about 25,000 mosquitos totaling at around 100,000. The traps were set up Tuesday.

West Nile virus is spread primarily through birds. West Nile is considered a flavivirus and Ball had previously compared the virus, and its family, to a bag of popcorn in the microwave. As the temperatures get hotter into the summer months, the virus expands inside of the bird and becomes more active. When the mosquito sticks its proboscis into the bird to drink its blood during hot days, the virus is transferred to the insect which then can pass it on to a human with a single bite.

"Our songbirds in our backyards, our waterfowl that migrate north and south and our corvid population like blue jays, crows, ravens, magpies and things like that are the ones that are the most susceptible to West Nile," Ball said. "So pretty much if it has a pulse, it has blood and it has feathers, it can carry West Nile and be a host for West Nile."

Ball said birds in the corvid family tend to get hit with the virus the hardest, adding that Butte County's magpie and jay populations has never fully recovered as a result of West Nile.

Every year, Ball and his team work to cull the mosquito population and inform the public of the dangers of West Nile, which similar to COVID-19, affects each person differently with the more severe cases causing serious illness and even life-long complications.

"One bite, one stick, and somebody potentially could have lifelong impairments, they may need to be hospitalized for a short amount of time, they could possibly die, all from one bite of a mosquito," Ball said.

Weather plays a large part in mosquito activity and how it varies from year to year. For example, Ball said consistent drought years can often see West Nile cases even earlier in the season thanks to heat arriving sooner. This year had considerable rainfall, adding to the insects’ spawning grounds which will likely mean more mosquitos than usual.

In Butte County, there are two species of mosquito that carry West Nile. Those are the Culex Tarsalis, often called the encephalitis mosquito and the Culex Pipiens, or house mosquito. The former can be found anywhere that there is water from rice fields to roadside ditches. House mosquitos stay true to their name and like to stay near humans and stick to man-made structures that hold water like pools, storm drains, buckets and even cups left outside.

The district spends much of its efforts controlling the populations of these insects and educating the public, but residents can mitigate the risk by dumping out standing water at their homes and checking storm drains for larvae. Mosquito fish can also help reduce the population in standing water like ponds and stream outlets.

Ball also urged the use of repellent when going outdoors.

"The repellents are safe," Ball said. "There's a huge misconception out there that this repellent or that repellent is dangerous. There are no factual studies that show any are dangerous."

Additionally, wearing protective, thick clothing that covers the arms and legs can also help reduce the risk of bites.

It might sound strange to some, but the summer months are considered the off-season for ticks by the district. Not because ticks aren't active in the parks and on the trails, but because the species that carry harmful diseases don't like the heat and dry grass.

"When the grass between (Oroville) and Chico is green, that's what we call tick season," Ball said, "When it's yellow, like it is now, and dead looking, it's not tick season. … We’ve got four common ticks in Butte County, two of which are what we call dry grass ticks or summer ticks. That's your American dog tick and your brown dog tick and you will find those abundantly out, and I’m not trying to pick on any place specifically, but I used to go on hikes with my dog around Horseshoe Lake at upper Bidwell Park and in all that tall grass, you can take your dog our there and come home with 22 ticks. But they cause no medical importance to humans or animals."

The problem ticks that like to come out when the hills and fields are green, like fall, winter and early spring, are the black-legged tick and the Pacific Coast Tick. Ball said these ticks can cause a host of problems like Lyme Disease, ongoing fevers and more, but they essentially go dormant in the summer.

Much like mosquitos, ticks can generally be kept away with repellent and covering clothing. Those who enjoy the outdoors should check themselves and their pets after spending time in the park or near tall grass.

One of the scarier-looking insects the district handles is the yellowjacket. A wasp that prefers making its home underground as opposed to on structures, like sheds, or on trees. While the district isn't permitted to do anything on structures, it is allowed to take care of in-ground yellowjacket nests.

"It's really easy to find yellowjackets," Ball said. "Wherever they’re flying around and you watch them disappear into your lawn or a shrub, that's where their nest is."

The reason there is a special focus on yellowjackets is that there is a higher risk of allergic reactions to their sting.

"It's a public health concern, and some people are more allergic to it," Ball said. "Some people go into what's called anaphylactic shock, and they can actually die if they don't have an epinephrine pen, or they don't seek medical attention very quickly — so we try to get rid of yellowjackets for people because of that."

Ball said the Mosquito and Vector Control District will take care of the ground nest free of charge.

The Butte County Mosquito and Vector District can be reached at 530-533-6038.

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