Mosquito and Vector Control
Santa Clara County mosquito and vector control services help residents address mosquito activity, standing water, rodents, and other animals or insects that can spread disease or cause injury. This article explains which services the County provides, how to report a problem or request an inspection, what information to prepare, and where service limitations apply. It also covers invasive day-biting mosquitoes, mosquito treatment alerts, free mosquitofish, and insect identification.
The Santa Clara County Mosquito and Vector Control District is the responsible office. Its work includes detecting and reducing vector-borne diseases, controlling mosquitoes, and helping the public resolve problems involving rodents, wildlife, and insects. A vector is an animal that can spread disease or cause discomfort or injury to people. Mosquitoes, ticks, rodents, and certain wildlife fall within that broad category, but the District’s response depends on the specific problem.
Services Available Through the District
The District provides free services that include mosquito inspections, mosquito activity reporting, standing-water reports, mosquitofish requests, insect identification, and exterior inspections for rodents and wildlife. Its official service directory also provides access to dead-bird reporting, coyote and mountain lion sighting reports, yellowjacket control requests, and requests for presentations or educational booths.
Choose the service that matches what you have observed. Mosquito bites or unusually high mosquito activity belong in a mosquito activity report. A neglected pool or persistent stagnant water belongs in a standing-water report. If you want a technician to look for breeding sources around your property, request a mosquito inspection. An unidentified insect can be submitted through the identification service, which has different procedures and limitations from an inspection.
These distinctions matter because reporting, identification, inspection, and removal are separate services. The District may inspect an exterior area and explain how to correct a problem without performing repairs, removing animals, or providing indoor pest control. Selecting the appropriate request helps establish what assistance you are seeking.
Mosquito Activity and Daytime Bites
Reporting Mosquitoes Around Your Property
The mosquito activity and day-biting mosquito reporting page provides separate reporting options for general mosquito activity and daytime bites. The District offers free exterior mosquito inspections in private and public spaces. Licensed technicians look for possible breeding sources, provide mosquito control, and explain measures that can prevent mosquitoes from continuing to breed.
When describing the problem, distinguish what you observed: numerous mosquitoes, repeated daytime bites, mosquitoes with black and white markings, or standing water that may be supporting breeding. These observations help explain why you are contacting the District. A report of daytime bites is particularly relevant to its invasive mosquito response.
Signs of Invasive Aedes Mosquitoes
Invasive Aedes aegypti mosquitoes have been detected in Santa Clara County. They are aggressive biters that often bite repeatedly during the day, frequently around the ankles. They are small, approximately one-quarter inch long, and have black and white stripes on their bodies and legs. They can also follow people indoors.
The District asks residents to report daytime biting, striped mosquitoes, and repeated bites around the ankles promptly. Its information about invasive Aedes aegypti mosquitoes explains their characteristics and the County’s response. These mosquitoes thrive near people in cities and backyards, where small containers can provide breeding sites.
Their presence does not mean that every mosquito carries disease. However, this species can transmit viruses including dengue, Zika, yellow fever, and chikungunya. The District monitors invasive mosquitoes because their establishment increases the potential for local disease transmission.
Backyard Access and Neighborhood Monitoring
In affected neighborhoods, District employees may go door to door to discuss mosquito activity, inspect outdoor areas, and control mosquitoes they find. With residents’ permission, technicians may place traps and bait stations in yards. Backyard access allows them to look for larvae and breeding containers that cannot be assessed from the street.
If you receive a District flyer or door hanger but miss the technician, contact the District to request a free mosquito inspection. Employees have clear identification as District staff. The District states that their activities on the property are limited to setting traps, checking for mosquitoes, and controlling mosquitoes found there.
Standing Water and Neglected Pools
Mosquitoes need stagnant water to reproduce, and a breeding source can be as small as a bottle cap containing water. Under favorable conditions, mosquitoes can develop from eggs into flying adults in less than a week. A large abandoned pool is a concern, but smaller sources such as plant saucers, buckets, and leaking irrigation equipment also deserve attention.
The standing-water and neglected-pool reporting service accepts reports involving puddles, overwatered lawns, broken sprinklers and leaks, neglected fountains, abandoned or neglected pools and jacuzzis, and water waste. You may submit an anonymous report about neglected pools or stagnant-water sources.
Describe the water source rather than relying only on a general statement that a property looks unmaintained. For example, distinguish a neglected fountain from irrigation runoff or an abandoned swimming pool. The service is directed at conditions that contribute to mosquito breeding.
The District does not respond to complaints about pools or jacuzzis being overchlorinated or underchlorinated. It also does not respond to complaints about debris in pools. A concern about pool chemistry or debris alone is different from a report about stagnant water and mosquito breeding.
What a Mosquito Inspection Covers
A free mosquito inspection request brings the problem to technicians who examine the exterior of the property for possible mosquito breeding sources. They can provide mosquito control and consultation about repairs, prevention, and measures to stop recurring breeding.
The service is exterior-only. Technicians do not conduct indoor inspections, enter crawl spaces or attics, climb onto roofs, or perform repairs. Advice about correcting a leaking fixture or another breeding source does not mean the District will complete that repair.
This limitation also applies when mosquitoes have been seen indoors. Indoor sightings can be relevant to a report, especially when invasive mosquitoes are suspected, but the inspection service remains focused on exterior conditions. Do not confuse the ability to report an indoor sighting with an offer of indoor inspection.
Free Mosquitofish for Artificial Water Features
Eligible Locations and Request Information
The District provides free mosquitofish to Santa Clara County residents and businesses for artificial bodies of water. Examples include ornamental ponds, unmaintained swimming pools and jacuzzis, watering troughs, fountains, and rain barrels. The mosquitofish request page explains what to include when requesting fish.
Prepare the following information before submitting the request:
The type of location where the fish will live, such as a pond, pool, trough, or rain barrel.
The approximate dimensions of the water feature, including its length, width, and depth.
Whether you can provide a five-gallon bucket or backyard access for delivery.
These details describe the proposed placement and delivery arrangement. The District’s service is for artificial water features of the types identified in its instructions; the request should identify the actual location where the fish will be housed.
Water Preparation and Fish Maintenance
The District instructs recipients to treat tap water with water conditioner to remove chlorine, chloramines, and ammonia before placing mosquitofish in it. Water preparation is a separate step from submitting the request and should be considered when preparing the intended water feature.
Mosquitofish prefer sunlit areas over shaded areas. Large rocks or shelter can protect them from opossums and raccoons. During winter, they may need limited feeding when mosquito larvae are scarce. These maintenance needs should be considered along with the suitability of the pond, fountain, or other artificial water feature.
Disease Monitoring and Mosquito Treatments
The District monitors mosquito abundance and disease activity throughout the year. Its surveillance includes diseases transmitted by native mosquitoes, such as West Nile virus, Western equine encephalitis, and St. Louis encephalitis, as well as monitoring for invasive mosquito species.
Technicians use traps to collect mosquitoes, then bring them to the laboratory. Mosquitoes are sorted by species, sex, and trap location into groups called pools. Laboratory testing uses polymerase chain reaction, or PCR, to detect disease in those groups. Here, a “pool” means a mosquito testing group, not a swimming pool.
Detecting West Nile virus in mosquitoes prompts adult mosquito control to reduce the mosquito population and lower the risk of human infection. For invasive mosquitoes, the District also uses methods such as removing standing water, placing mosquitofish, treating larvae, and deploying bait stations.
Larvicides target mosquito larvae before they become flying, biting adults. Adulticides target adult mosquitoes and are used when needed to quickly prevent disease spread or reduce invasive mosquito spread. A neighborhood treatment notice therefore concerns a specific control activity; it is different from an individual property inspection request.
Countywide Alerts and Neighborhood Notifications
The official mosquito alerts page explains two notification options. General mosquito alerts provide countywide information by email, including scheduled treatments, ZIP codes and maps, treatment times, significant mosquito activity, and links to official advisories. Subscribers may unsubscribe at any time.
AlertSCC provides neighborhood-specific notifications and is also the County’s official emergency alert and warning system. Depending on the selected notification methods, messages can arrive by email, phone call, or text. Enrollment requires creating an account through the enrollment system, logging back in to choose alerts, and selecting “Santa Clara County” to receive mosquito notifications.
Choose the option that matches the information you want. General alerts cover activity throughout the county, while AlertSCC offers neighborhood notifications and other County emergency messages. Neither subscription replaces a service request when you need to report mosquitoes or ask for an inspection.
Reducing Breeding Around Your Home
The District recommends inspecting property for standing water weekly. Drain or turn over items that hold water, including flowerpots, planter bases, buckets, old tires, and outdoor pet dishes. Clean birdbaths and pet bowls weekly to remove mosquito eggs rather than simply adding fresh water.
For invasive Aedes mosquitoes, cleaning container surfaces matters because eggs can remain attached to the sides. Scrub outdoor items that collect water, cover outdoor trash cans and recycling bins, and keep water-holding objects away from rain and sprinkler spray.
Keep rain gutters clear so water can flow. Screen or seal rain barrels, cisterns, and irrigation drains to prevent mosquito access. Repair leaking faucets and broken sprinkler heads, and avoid overwatering lawns and plants. Swimming pools need adequate water levels for circulation and filtration.
Window and door screens should fit tightly and have no holes or tears. For outdoor bite protection, the District recommends long sleeves, long pants, socks, and closed-toe shoes, along with insect repellents containing EPA-registered ingredients such as DEET, picaridin, IR3535, or oil of lemon eucalyptus. Follow product label instructions.
Mosquitoes associated with West Nile virus are most active around dawn and dusk, so the District recommends limiting outdoor activity at those times. Invasive day-biting mosquitoes require attention during daytime activities as well. Avoid treating a lack of evening bites as evidence that there is no mosquito problem.
Insect Identification and Specimen Preparation
Free insect identification services are available to County residents and businesses. This service identifies submitted insects and provides management recommendations. It does not include spraying for insects or arthropods, property inspections, or recommendations about which private pest control company to hire.
Physical Specimens and Photographs
Actual insects are preferred because staff can examine them under a microscope. Fresh specimens are preferable to old specimens, and live insects are accepted. Photographs are also accepted, although image quality may make identification difficult and staff may request a physical insect.
Do not use tape to catch an insect; removing it can damage the specimen. Free sticky traps are available on request. Place the insect or sticky trap in a clear resealable bag without crushing it, and include your name, address, phone number, or email on the bag or on paper inside or attached to it.
The District does not search through earwax or other human substances, vacuumed dust, clothing, or curtains to locate specimens. Submit the insect itself or a photograph rather than a collection of materials that staff would need to sort through.
Submission Methods and Identification Results
Specimens may be dropped off at the front counter or mailed to the District, addressed to the attention of Vector Ecologists. For mailed submissions, place the specimen inside a box rather than an envelope to prevent crushing. The insect identification page specifies counter drop-off hours of Monday through Friday, 7:30 a.m. to 3:00 p.m., excluding County holidays.
Photographs may be emailed to vectorinfo@cep.sccgov.org. Use “Insect ID” in the subject line and include a brief description of where the insect was collected. After processing the insect, staff will contact you within three business days with identification results and management recommendations. An official identification letter is available on request for submission to code enforcement or other agencies.
Rodent Inspections and Property Concerns
The District’s rodent inspection service provides free exterior inspections. Technicians look for possible entry points and conditions attracting rodents, then advise on repairs, trapping, and safe cleanup.
The District does not trap or remove rodents, clean up after them, inspect indoors, enter crawl spaces or attics, climb roofs, or perform repairs. An inspection report documents the problem and provides guidance; it is not a removal or cleanup service.
Tenants whose property owners have not responded to rodent concerns can request an inspection and take the official report to their city’s code enforcement agency. For property in an unincorporated area, the relevant destination is County code enforcement. A more detailed inspection report may be provided on request.
The Mosquito and Vector Control District is not a law enforcement agency and cannot fine or penalize a property owner. Its documentation and the enforcement process serve different purposes, so a tenant seeking enforcement must bring the documentation to the appropriate city or County agency.
Wildlife, Dead Birds, and Yellowjackets
Free exterior wildlife inspections and consultations address problems involving coyotes, opossums, raccoons, snakes, skunks, and bats. Technicians identify possible entry points and attractants and explain repairs and ways to reduce access to food, water, and shelter.
Wildlife inspections do not include trapping or relocating animals, cleanup, indoor entry, roof access, or repairs. The District does not respond to sick or injured wildlife, domestic animal situations, emergency or hazardous conditions, or wildlife requests after the service’s stated working hours of Monday through Friday, 7:30 a.m. to 3:00 p.m.
Coyote and mountain lion sighting reports are for data collection only. Submitting a sighting does not request animal capture or emergency response. Dead-bird reporting is a separate service: the District picks up certain dead birds for West Nile virus testing, rather than providing general removal of live or dead animals.
Yellowjacket control also has a defined scope. The District provides free control in public areas, while private property control is assessed by a technician. It does not provide nest removal or relocate bee swarms. The service directory’s yellowjacket request should therefore be understood as a control request, with the limitations described on the individual service page.
Office Hours and Service Communications
The District’s general office hours are Monday through Friday, 7:30 a.m. to 3:30 p.m., except County holidays. Some services specify an earlier cutoff, including insect specimen drop-off and wildlife service requests. Match your visit or request to the hours stated for that service.
If staff cannot answer your call, leave a detailed voicemail with your name, contact information, and reason for calling. The District states that a team member will return the call as soon as possible. Describe the service you need, such as a mosquito inspection, mosquitofish delivery, or rodent inspection, so your message clearly identifies the issue.
Use the designated service request or reporting option rather than the website’s “Was this page helpful?” feedback form. That feedback form asks users not to include personal information such as a home address, tax identification number, or Social Security number. It serves a different purpose from requesting field assistance.
Mosquito and Vector Control Office
Santa Clara County Mosquito and Vector Control District
1580 Berger Drive
San Jose, CA 95112
Phone: (408) 918-4770
Mosquito and Vector Control FAQs
Can mosquito eggs survive in a dry container?
Yes. Invasive Aedes aegypti eggs can survive for months without water. They attach to container surfaces and may look like thin lines of dirt. When water returns and conditions are suitable, the eggs can hatch. An empty bucket, plant saucer, or outdoor toy therefore may still contain eggs even when no larvae are visible. Before putting a previously dry container back into use, scrub its water-holding surfaces. Simply letting it dry does not reliably eliminate the eggs.
Do ankle-biting mosquitoes usually come from nearby?
Invasive Aedes aegypti mosquitoes generally stay within about 500 feet of where they hatch, according to the District’s information about invasive mosquitoes. Repeated bites in one outdoor area can point to a breeding source nearby, although they do not identify a particular property. If your yard has no obvious standing water, that does not rule out a neighborhood source. Small containers on surrounding properties can support breeding, which helps explain why the District monitors nearby streets and yards rather than only the location where someone reported bites.
Can I accidentally move invasive mosquitoes elsewhere?
Yes. These mosquitoes can spread by hitching rides with people and belongings. Their eggs can attach to tires and plants such as lucky bamboo, while adult mosquitoes may follow people into cars. Moving a water-holding item can transport eggs even after the water is gone. Before moving outdoor containers between properties, check and clean them rather than assuming that a dry item cannot carry mosquitoes.
Why did I get a treatment email without subscribing?
For invasive mosquito treatments, the District states that it obtains email addresses for residents in affected neighborhoods from the County of Santa Clara Registrar of Voters. Those residents may receive scheduled-treatment notices even if they did not subscribe to general mosquito alerts. Receiving that email does not, by itself, mean mosquitoes were found on your individual property; the notification concerns treatment planned for the affected neighborhood.