A: Yes—on a small scale. It is not uncommon to occasionally see one or two mosquitoes on warm days in early spring (for example, around Easter). However, the number of mosquitoes currently being observed is higher than what we typically expect for March.

Permethrin is a type of synthetic pyrethroid that targets the nervous system of insects, including mosquitoes. It works by disrupting sodium channels in nerve cells, which are essential for normal nerve signal transmission. In mosquitoes, this disruption leads to paralysis and death.

The reason permethrin is much more toxic to mosquitoes than to humans and other mammals comes down to several important biological differences:

• Greater Sensitivity in Insects: Mosquitoes and other insects have sodium channels that are more sensitive to permethrin, making them highly susceptible even at very low doses.
• Body Size and Dose: The amount of permethrin used in mosquito control is extremely small (ultra-low volume applications). Relative to body size, mosquitoes receive a much higher effective dose than humans or pets would from environmental exposure.
• Faster Metabolism in Mammals: Humans and other mammals have more advanced metabolic systems, including liver enzymes that rapidly break down and eliminate permethrin from the body before it can accumulate to harmful levels.
• Lower Absorption Through Skin: Permethrin is poorly absorbed through human skin compared to how easily it affects insects through direct contact.
• Application Methods: Mosquito control programs apply permethrin in very fine droplets during specific times (typically evening hours) to target active mosquitoes while minimizing exposure to people, pets, and other non-target organisms.

When used according to EPA-approved label directions, permethrin has been extensively evaluated and is considered safe for use in public health mosquito control programs.

The Four Rivers Vector Control District was established in 1985 through a community petition and public hearing process, in accordance with Oregon law (ORS 452.020). Since then, our mission has been to protect public health by reducing vectors—organisms that can spread disease—throughout our service area.

Today, our primary focus is mosquito control, as mosquitoes are the most common vector found in large numbers across the district.

Mosquito control districts like ours play an important role in monitoring and managing mosquito populations to help reduce the risk of diseases such as West Nile virus, Zika virus, dengue fever, and malaria. Our team regularly conducts surveillance to track mosquito activity, locate breeding areas, and respond quickly when populations increase.

We use a combination of science-based methods to keep mosquito numbers down, including:

• Treating standing water where mosquitoes develop (larviciding)
• Targeted fogging when necessary (adulticiding)
• Reducing breeding habitats whenever possible (source reduction)
•  

Our goal is simple: to help keep our community safe, comfortable, and informed throughout mosquito season.

That’s a great question, and we understand your concern. Your property taxes support the District’s work, and our goal is to provide the greatest benefit to the entire community.

Our program focuses on community-wide mosquito control, meaning we target mosquitoes at their source—such as wetlands, standing water, and breeding habitats. This approach is the most effective way to reduce mosquito populations and protect public health across the entire District, rather than treating individual properties alone.

That said, if conditions on or near your property are contributing to a broader mosquito issue, our technicians will evaluate the area. If treating your property helps address the larger community problem, we will take appropriate action as part of our program.

In some cases, fogging down a driveway or access route may help improve control in the surrounding area. We are happy to do this when it supports overall mosquito reduction—just let us know that access is permitted. For safety and efficiency, we ask that driveways, trails, and access paths are clear of vehicles, obstacles, or hazards.

Please note that while our staff operate equipment carefully, the District is not responsible for any incidental damage (such as backing into objects or running over items) when accessing private property. Ensuring clear access helps us perform services safely and effectively.

Routine treatments of private yards, patios, or driveways solely for personal comfort are generally outside the scope of District services, as they require different resources, permissions, and liability coverage. However, we are always happy to:

• Provide guidance on reducing mosquito habitat around your home
• Recommend effective prevention strategies or products
• Answer any questions you may have

If you are planning a special event—such as a wedding, party, or gathering—we understand the importance of minimizing mosquitoes. While we will do our best to assist when possible, we recommend contacting a licensed private applicator for guaranteed, site-specific treatment to ensure your event is as comfortable as possible.

We appreciate your understanding and your partnership in helping us protect the community from mosquitoes.

A: Fogging will begin as soon as:

1. Weather conditions are consistently suitable, and
2. Our permitted treatment season opens in April

We are committed to starting as early as safely and legally possible.

Our mosquito control program is based on science, surveillance, and public health need—not a fixed calendar schedule. Treating neighborhoods on a set rotation, regardless of mosquito activity, is not considered effective or environmentally responsible.

Instead, we focus our efforts where and when they are needed most by using:

• Mosquito surveillance data (trap counts and species identification)
• Landing rate counts (measuring mosquito activity in an area)
• Service requests from residents
• Environmental conditions (weather, water levels, and habitat)

We are continuously working throughout the District treating larval habitats such as river edges, wetlands, and standing water to prevent mosquitoes from developing. Adult mosquito control (fogging) is conducted only when populations reach established thresholds and treatment is necessary to reduce nuisance levels or potential public health risks.

When adult mosquito treatments are scheduled, the areas to be treated are posted on our website in advance so residents can stay informed.

If you submit a mosquito Service Request, it becomes part of our decision-making process. A technician will evaluate the area, and if thresholds are met, treatment will be scheduled at the most effective time.

This targeted approach ensures we use the right tools, in the right place, at the right time—protecting both public health and the environment.

DEET-based repellents work best at repelling mosquitoes. They also offer other DEET alternatives that work well such as picaridin which offers a close second to the effectiveness of DEET.

DEET concentrations start out at 5% (provides approx. 90 minutes of protection) and go all the way up to 100% DEET (approx. 10 hrs. of protection). Pick a concentration level that will meet your outdoor activity. The American Academy of Pediatrics says that all family members over the age of two months can use DEET-based repellents with up to 30% concentration with confidence.

Mosquito coils and Therma-Cell brand devices can also help provide some protection. Our favorite mosquito repellent is Proven Insect Repellent, it contains picaridin and is scent-free.

While mosquito control efforts help reduce populations across the district, homeowners play an important role in protecting themselves and their property. A few simple steps can make a big difference:

1. Eliminate Standing Water

Mosquitoes lay their eggs in standing water, and even small amounts can become breeding sites. Check your yard regularly for:

• Buckets, flower pots, and trays
• Birdbaths (refresh water at least weekly)
• Clogged gutters
• Old tires or containers
• Tarps or low spots that collect water

2. Maintain Your Yard

Keep grass trimmed and vegetation managed. Mosquitoes like to rest in shady, overgrown areas during the day.

3. Use Personal Protection

When mosquitoes are active (especially at dawn and dusk):

• Apply EPA-approved insect repellent
• Wear long sleeves and pants when possible
• Consider using fans when outdoors—mosquitoes are weak fliers

4. Check Screens and Doors

Make sure window and door screens are in good condition to keep mosquitoes out of your home.

5. Reduce Outdoor Attractants

Limit outdoor lighting when possible, as it can attract insects (and mosquitoes that feed on them).

Working Together

Mosquito control is most effective when the community works together. By reducing breeding areas around your home and taking simple precautions, you can significantly lower your risk of mosquito bites.

If you’re experiencing high mosquito activity in your area, please let us know so we can respond as quickly as possible.

Mosquitoes have an average adult life span that typically lasts 3-6 weeks.

Mosquitoes go to these cooler, humid shady areas during the daytime to rest and escape the hot dry air that can quickly kill them. Maintaining your yard by cutting down tall grass and weeds will reduce the harborage areas and the number of mosquitoes in your yard.

In public health, a vector is any living organism that can transmit pathogens (such as viruses, bacteria, or parasites) from one host to another. Vectors play a critical role in the spread of many diseases that affect humans and animals.

The most common vectors are insects and arthropods, including:

• Mosquitoes
• Ticks
• Fleas
• Flies

For example, mosquitoes are well-known vectors because they can carry and transmit diseases such as West Nile virus, malaria, and dengue. When a mosquito feeds on an infected host, it can pick up a pathogen and later transmit it to another host during subsequent bites.

Not all mosquitoes or insects carry disease—however, monitoring and controlling vector populations helps reduce the risk of disease transmission and protects public health.

This is why vector control programs focus on reducing populations of these organisms and minimizing human contact with them.

We appreciate you helping us monitor mosquito activity in the community. If you are experiencing increased mosquito presence, please let us know by submitting the Mosquito Activity Notification Form on our website or by calling our office at (541) 593-1689.

While we do not provide on-demand or immediate service calls, all reports are important and help guide our surveillance and response efforts. Once your request is received, a technician will evaluate the area and schedule treatment at the time it will be most effective and efficient, as soon as possible.

Your input plays an important role in helping us protect public health—thank you for partnering with us!