Mosquito & Vector News

Positive West Nile Virus Mosquitoes Found in Portion of Milpitas

From the County of Santa Clara
June 29, 2022

Targeted adult mosquito control treatment scheduled for Thursday, June 30 in a limited area within Milpitas

SANTA CLARA COUNTY, CALIF. – The County of Santa Clara Vector Control District has confirmed the presence of West Nile virus (WNV) positive mosquitoes in an area of Milpitas (ZIP Code 95035). Weather permitting, this area will be treated to reduce adult mosquito populations with the use of truck-mounted equipment on Thursday, June 30, starting around 10 p.m., and will conclude a few hours later.

The Vector Control District has a dedicated surveillance program to detect the presence of diseases like West Nile virus, St. Louis encephalitis, and western equine encephalitis, all of which are transmitted through the bite of infected mosquitoes. The data collected through surveillance is used to predict locations that are more likely to have these disease-transmitting mosquitoes. When a WNV-positive mosquito is detected, the District initiates an adult mosquito control treatment to reduce the mosquito population in the area, which reduces the risk of a WNV human infection.

The District has been conducting truck-mounted treatments regularly since 2003 to successfully reduce WNV-transmitting mosquito populations. The District will be adhering to requirements and recommendations from the County of Santa Clara Public Health Department for COVID-19.

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Mosquito that carries yellow fever detected in Butte County

From Action News Now
June 28, 2022

BUTTE COUNTY, Calif. – The mosquito that carries yellow fever has been confirmed in Butte County.

This is the third year in a row that Butte County Mosquito and Vector Control has found one of the Aedes Aegypti. 

It can carry other viruses too, like Dengue and Zika.

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Standardised bioassays reveal that mosquitoes learn to avoid compounds used in chemical vector control after a single sub-lethal exposure

Posted by Vector and Vector-borne Disease Committee
June 27, 2022

Seynabou Sougoufara, Hanna Yorkston-Dives, Nurul Masyirah Aklee, Adanan Che Rus, Jaal Zairi & Frederic Tripet

Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Stafforshire, United Kingdom;   Vector Control Research Unit, School of Biological Sciences, Universiti Sains Malaysia, George Town, Malaysia

Nature Sci Rep 12, 2206 (2022). https://doi.org/10.1038/s41598-022-05754-2

Abstract.  Vector-borne diseases are worldwide public health issues. Despite research focused on vectorial capacity determinants in pathogen transmitting mosquitoes, their behavioural plasticity remains poorly understood. Memory and associative learning have been linked to behavioural changes in several insect species, but their relevance in behavioural responses to pesticide vector control has been largely overlooked. In this study, female Aedes aegypti and Culex quinquefasciastus were exposed to sub-lethal doses of 5 pesticide compounds using modified World Health Organization (WHO) tube bioassays. Conditioned females, subsequently exposed to the same pesticides in WHO tunnel assays, exhibited behavioural avoidance by forgoing blood-feeding to ensure survival. Standardized resting site choice tests showed that pre-exposed females avoided the pesticides smell and choose to rest in a pesticide-free compartment. These results showed that, following a single exposure, mosquitoes can associate the olfactory stimulus of pesticides with their detrimental effects and subsequently avoid pesticide contact. Findings highlight the importance of mosquito cognition as determinants of pesticide resistance in mosquito populations targeted by chemical control.

Note:  Although this study has greatest relevance for control programs using indoor surface sprays and impregnated bed nets, the concept of learning behavior in mosquitoes is intriguing and may have important implications for the use of home fumigation products. 

Summer ushers in West Nile Virus in San Joaquin County

From Yahoo News
June 25, 2022

Jun. 25—STOCKTON — The San Joaquin County Mosquito and Vector Control District announced Thursday that its mosquito-borne disease surveillance program recently detected West Nile virus (WNV) in six samples of mosquitoes found in the 95209 and 95219 ZIP codes.

The 95209 ZIP code is located in Stockton east of Interstate 5 and north of Hammer Lane. The 95219 ZIP code is located west of I-5.

“These WNV positive mosquitoes are the first indicator that WNV is active in San Joaquin County this year,” district spokesman Aaron Devencenzi said. “As temperatures rise during the summer months, so will mosquito populations. West Nile virus will amplify within the mosquito population, leading to an elevated risk of WNV in humans.”

The district said it will increase is adult mosquito control activities now that WNV has been detected in the county, and planned to conduct ground spraying in the northwest Stockton Friday or Saturday between Stanfield Drive, Mosher Slough, Thornton Road and Bainbridge Palce.

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Southern California is now a mosquito zone. Here’s how to defend yourself

From the Los Angeles Times
June 24, 2022

Summer is here and so are the mosquitoes in your backyard, waiting to nibble at your ankles. And elbows. And earlobes.

Not coincidentally, the start of the season is also National Mosquito Control Awareness Week, when the American Mosquito Control Assn. and other experts share tips for keeping these bloodsucking pests away.

Like most blood-feeding insects, mosquitoes are attracted to humans from a distance by the carbon dioxide we exhale, said Daniel Markowski, the AMCA’s technical advisor. Once they get close, they use a variety of other cues, such as shapes, sizes and colors, to home in on their hosts.

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West Nile Virus detected in Merced County. Here’s how residents can take precautions

From the Merced Sun-Star
June 21, 2022

The year’s first local confirmation of West Nile Virus was announced by the Merced County Mosquito Abatement District Tuesday, along with an appeal to the public to help suppress mosquito activity.

No human cases have been detected in Merced County at this time, but a mosquito pooled sample collected in the City of Merced recently tested positive for the virus, according to an abatement district news release.

Although no positive human cases have been reported yet this year, the public should citizens should still be concerned, as more confirmations of the virus will likely ensue in the following weeks, the release said.

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A Review of Zoonotic Disease Threats to Pet Owners: A Compendium of Measures to Prevent Zoonotic Diseases Associated with Non-Traditional Pets: Rodents and Other Small Mammals, Reptiles, Amphibians, Backyard Poultry, and Other Selected Animals

Posted by Vector and Vector-borne Disease Committee
June 21, 2022

Kate Varela, Jennifer A. Brown, Beth Lipton, John Dunn, Danielle Stanek and NASPHV Committee Consultants

VECTOR-BORNE AND ZOONOTIC DISEASES 22 (6), 2022;  DOI: 10.1089/vbz.2022.0022

Authors’ Summary.  As ownership of non-traditional pet (NTP) species is increasing, the number and size of outbreaks associated with NTPs in recent years has also increased. Non-traditional pet owners and members of the public who may come into contact with NTPs should be aware of the potential health risks and understand that even apparently healthy animals can transmit pathogens. The recommendations in this Compendium provide public health professionals, animal health professionals, industry, and healthcare providers (including veterinarians, physicians, and allied health professionals) resources to prevent disease transmission and spread. These recommendations aim to benefit all partners by preventing human infections, maintaining animal health and welfare, and providing economic benefits.

Note:  The publication reviews useful information about health problems related to pets, including back yard chicken flocks.  As these pets become more widespread, vector control districts as well as veterinarians undoubtedly will be contacted to resolve public health issues, including arthropod infestations.  

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Duration of West Nile Virus Immunoglobulin M Antibodies up to 81 Months Following West Nile Virus Disease Onset

Posted by Vector and Vector-borne Disease Committee
June 21, 2022

  1. Erin Staples,1* Katherine B. Gibney,1,2, Amanda J. Panella,1 Harry E. Prince,3 Alison J. Basile,1  Janeen Laven,1  James J. Sejvar,4  and Marc Fischer1

1Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado; 2Epidemic Intelligence Service Program, CDC, Atlanta, Georgia; 3Quest Diagnostics Infectious Disease, Inc., San Juan Capistrano, California; 4Division ofHigh-Consequence Pathogens and Pathology, CDC, Atlanta, Georgia

Am. J. Trop. Med. Hyg.;  doi:10.4269/ajtmh.21-1234

Abstract. West Nile virus (WNV) IgM antibodies typically indicate a recent infection. However, WNV IgM antibodies can remain detectable for months to years following illness onset. We found that 23% (11/47) of samples tested with a WNV ELISA and 43% (20/47) of samples tested with WNV microsphere immunoassay (MIA) at 16–19 months following WNV illness onset were positive for IgM antibodies. The proportion of samples testing positive for WNV IgM by ELISA decreased over time, but 5% (2/44) of individuals remained positive at 60–63 months after their acute illness and 4% (2/50) were WNV IgM equivocal at 72–81 months. Clinicians and public health officials should consider these findings along with clinical and epidemiologic data when interpreting WNV IgM antibody test results.

Note:  WNV surveillance programs frequently make decisions concerning adulticide applications based on reported human cases.  This study indicates that laboratory confirmation of suspect cases based on IgM ELISA could be the result of previous exposure and not due to recent infection.  Careful evaluation of case data combined with mosquito and mosquito infection data should be included in application decisions. 

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Mosquito Week signals mosquito season nears

From the Daily Republic
June 17, 2022

FAIRFIELD — The recognition of National Mosquito Control Awareness Week lets area residents know the height of the mosquito season is closing in fast.

“National Mosquito Control Awareness Week, celebrated June 19-25 throughout the country, is a good time for community members to ensure they are doing their part to protect themselves from mosquito-transmitted diseases,” Assemblyman Bill Quirk, D-Hayward, said in a statement released by the Mosquito Vector Control Association of California. “Residents can take simple steps to help eliminate mosquitoes from their community and protect themselves from mosquito bites.”

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Free mosquitofish can reduce breeding

From the Manteca Bulletin
June 16, 2022

Free distribution of mosquitofish will be available to residents of Ripon, Manteca, Lathrop and the surrounding San Joaquin County areas.

This was announced Wednesday by the San Joaquin County Mosquito & Vector Control District.

The mosquito fish is a natural and effective way of fighting the breeding of mosquitos. Some species can pose major public health concerns by transmitting anything from the West Nile Virus to malaria and encephalitis.

According to SJC Mosquito & Vector Control District, each fish can eat 80 to 100 mosquito larvae and pupae per day.

A maximum of 15 fishes – ideally placed in ornamental ponds, neglected swimming pools, and animal water troughs – will be provided to residents of cities and rural areas of the county. Required will be a name, address and the location of where the fish will be placed.

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OCMVCD Showcases a New Educational Tool and Partnerships During National Mosquito Awareness Week

From OCMVCD
June 15, 2022

Garden Grove, CA.  June brings warm weather, more mosquitoes, and National Mosquito Awareness Week. To increase awareness of mosquitoes and the diseases they can transmit, Orange County Mosquito and Vector Control District (OCMVCD) is expanding partnerships with local agencies and promoting new educational resources for residents.

During National Mosquito Control Awareness Week, June 19-25, OCMVCD is launching the Tip, Toss, Take Action campaign and promoting Grandmother Mosquito, a new children’s book teaching families about mosquito breeding. To increase awareness and educational outreach, OCMVCD will be interacting with the public in the following ways:

  • Partnering with OC Public Libraries’ Storytime series to promote a new children’s book called Grandmother Mosquito.
  • Engaging with residents at the Discovery Cube of Orange County with activities, crafts, and opportunities to speak with experts on June 18th.
  • Releasing an “Ask the Expert” video series that allows community members to submit questions to OCMVCD experts.
  • Hosting giveaways and trivia questions. 

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National Mosquito Awareness Week starts on June 19

From New Santa Ana
June 15, 2022

Garden Grove, CA. June brings warm weather, more mosquitoes, and National Mosquito Awareness Week. To increase awareness of mosquitoes and the diseases they can transmit, Orange County Mosquito and Vector Control District (OCMVCD) is expanding partnerships with local agencies and promoting new educational resources for residents.

During National Mosquito Control Awareness Week, June 19-25, OCMVCD is launching the Tip, Toss, Take Action campaign and promoting Grandmother Mosquito, a new children’s book teaching families about mosquito breeding. 

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West Nile-positive mosquitoes found

From the Antelope Valley Press
June 15, 2022

LANCASTER — The Valley has seen its first finding of mosquitoes carrying West Nile virus this season, officials from the Antelope Valley Mosquito and Vector Control District said.

Mosquitoes carrying the virus were found in a trap in the vicinity of 40th Street East and Avenue J-8. Vector Control District officials will place additional traps and closely monitor this area.

“These positive mosquito samples are a good reminder that West Nile virus is active in the Antelope Valley and that residents need to be vigilant about personal mosquito control measures,” District Manager Leann Verdick said in a release announcing the findings.

West Nile virus is endemic to the state and is carried by the native culex mosquitoes.

People bitten by an infected mosquito may experience flu-like symptoms that can include fever, body aches, skin rash and fatigue.

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What You Should Know about the West Nile Virus

From NBC Los Angeles
June 13, 2022

What is the West Nile Virus?

The “West Nile Virus” was first identified in the sub-region of Uganda called The West Nile.

The virus runs during mosquito season, which takes place from summer through fall. It is present within all states of the continental U.S.

The virus survives within several types of birds and is transmitted when a mosquito feeds off of an infected bird. The disease can infect humans, horses, and birds.

It is the most common vector-borne virus in California with more than 7,000 human cases and over 300 deaths in California since 2003.

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Mosquitoes test positive for West Nile virus in L.A. County

From KTLA
June 13, 2022

A mosquito tested positive for West Nile virus in Los Angeles County, marking the first such sample this year, health officials announced Monday.

The positive mosquito sample was collected from a mosquito trap in Bellflower, confirming the presence of the virus in mosquito populations within the community, according to the Greater Los Angeles County Vector Control District.

While this confirmation serves as the first positive mosquito sample this year, West Nile virus was detected in three dead crows found in the North Hills neighborhood on May 26, the agency said.

Surveilling dead birds serves as an early warning detection tool that helps authorities identify when the virus is actively being transmitted between birds in the area.

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Mosquitoes Collected in Thermal Test Positive for West Nile Virus

From NBC Palm Springs
June 8, 2022

THERMAL (CNS) – Mosquitoes collected in Thermal tested positive for West Nile virus, the first detection of the virus in the city this year, the Coachella Valley Mosquito and Vector Control District announced today.

The mosquitoes were collected near 68th Avenue and Fillmore Street in Thermal, according to the district.

In response, mosquito-control technicians increased their presence in the Coachella Valley, carrying out control treatments in hopes of reducing any spread of the virus. District officials, however, urged residents to take precautions.

“Before going out, apply insect repellent containing the EPA-registered ingredients,” district public information officer Tammy Gordon said in a statement. “There is no cure or vaccine for West Nile virus, it’s not worth getting sick.”

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Prepare for West Nile Virus season as temperatures heat up

From Gold Country Media
June 7, 2022

The Placer Mosquito and Vector Control District encourages area residents to prepare now for West Nile virus season by protecting themselves from potential mosquito bites.

With no cure available, West Nile virus is a serious and potentially fatal illness transmitted through the bite of a female mosquito.

Although West Nile Virus has not yet been detected in Placer County this season, the district’s public information officer Meagan Luevano said, the virus has been detected in Yolo and Sacramento counties.

A dead bird that tested positive for West Nile virus was found two weeks ago in Davis and a positive pool of mosquitoes was found last week in Carmichael, according to Luevano..

“The detections are super close to us,” Luevano said. “These detections are not that much earlier than our detections last season. Our first West Nile virus positive mosquito sample was June 23 last year.”

Placer County had one human case of the virus last year.

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Dead Birds in North Hills Test Positive for West Nile Virus

From SCV News
June 7, 2022

The Greater Los Angeles County Vector Control District has confirmed the first detection in 2022 of West Nile virus activity in Los Angeles County. The virus was detected in three dead American crows collected in the neighborhood of North Hills Zip Code 91343 on May 26.

This confirmation serves as the District’s first detection of West Nile virus activity in 2022. Mosquito samples have not tested positive for the virus within the surrounding community, nor in Los Angeles County. The dead bird surveillance program serves as an early warning detection tool that helps identify when the virus is actively being transmitted within the bird population. The three dead birds were collected, shipped and tested at the university of California, Davis Arbovirus Research and Training Laboratory which provides testing for multiple vector control agencies across the state.

“American crows can fly up to 40 miles each day from overnight roosting sites, so while there has not yet been virus activity detected in mosquito populations in Los Angeles County, this confirmation serves as an alert that mosquitoes may soon become infected and residents should take precautions,” said Director of Scientific-Technical Services Steve Vetrone.

Since West Nile virus is endemic to Los Angeles County, it is typically detected by local public health agencies during summer. Because there is no human vaccine for West Nile, residents must be proactive against mosquito bites by wearing insect repellent. The Centers for Disease Control and Prevention recommend products with the active ingredients DEET, Picaridin, IR3535, or oil of lemon eucalyptus as being safe and effective against mosquitoes that can transmit disease when used according to the labels.

One in five persons infected with the virus will exhibit symptoms. Symptoms can include fever, headache, body aches, nausea, or skin rash. These symptoms can last for several days to months. One in 150 people infected with the virus will require hospitalization. Severe symptoms include high fever, muscle weakness, neck stiffness, coma, paralysis and possibly death. If residents feel they are experiencing symptoms, it is strongly recommended to consult their primary care physician.

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3 dead crows found in North Hills test positive for West Nile virus

From CBS Los Angeles
June 6, 2022

West Nile virus has been confirmed in Los Angeles County for the first time this year, authorities said Monday.

The virus was detected in three dead crows collected in the North Hills area on May 26, according to the Los Angeles County Vector Control District. Mosquito samples had not tested positive for the virus in Los Angeles County yet.

“American crows can fly up to 40 miles each day from overnight roosting sites, so while there has not yet been virus activity detected in mosquito populations in Los Angeles County, this confirmation serves as an alert that mosquitos may soon become infected, and residents should take precautions,” Steve Vetrone, director of Scientific-Technical Services, said in a statement.

There is no human vaccine for West Nile virus, which is usually transmitted via mosquito bite. Symptoms of West Nile include fever, headache, body aches, nausea, or skin rash that can last for several days to months. One of 150 people will require hospitalization, and severe symptoms include coma, paralysis, and death, authorities said.

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West Nile virus found in Montgomery County mosquitoes, officials say

From ABC 13
June 6, 2022

MONTGOMERY COUNTY, Texas (KTRK) — Officials confirmed a case of West Nile virus has been found in The Woodlands’ first mosquito samples of the 2022 season.

The mosquitos were caught through the course of the week in zip codes 77380 and 77382.

According to city officials, treatment of the affected areas will begin Tuesday, including spraying all streets and county rights of way. The second round of treatment is scheduled for Thursday.

“Our office is working diligently to minimize the risk of contracting a mosquito-borne illness,” Precinct 3 Commissioner James Noack said.

Residents can check the treatment activity map to learn when spraying will occur in their neighborhoods.

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Evaluation of the effectiveness of the California mosquito-borne virus surveillance & response plan, 2009-2018

Posted by Vector and Vector-borne Disease Committee
June 6, 2022

Mary E. Danforth1, Robert E. Snyder1, Emma T. N. Lonstrup2, Christopher M. Barker2, Vicki L. Kramer1ID

1 Vector-Borne Disease Section, California Department of Public Health, Sacramento, CA,

2 Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA

PLoS Negl Trop Dis 16(5): e0010375. https://doi.org/10.1371/journal.pntd.0010375

Abstract [partial].  …  We built models to determine the association between risk level and the number of reported symptomatic human West Nile disease cases with onset in the following three weeks to identify the essential components of the risk level and to compare California’s risk estimates to vector index. Risk level calculations based on Culex tarsalis and/or Cx. pipiens complex levels were significantly associated with increased human risk, particularly when accounting for vector control area

and population, and were better predictors than using the vector index. Including all potential

environmental components  created an effective tool to estimate the risk of WNV transmission

to humans in California.

Note.   There has been a trend among MVCAC agencies to reduce the number of surveillance components used to monitor WNV transmission risk.  Currently fewer agencies report and test dead birds, and deploy chicken flocks each year.  These components have been replaced by increased mosquito trapping and testing, and the calculation of the Vector Index.  The current analyses show that the inclusion of avian host as well as mosquito infection data enhances estimates of human disease risk. 

West Nile Virus Still a Threat to Horses Despite Drought

From aginfo.net
June 1, 2022

While much of the western U.S. endures widespread drought, people may think mosquito season won’t be as intense. However, just because there’s no rain doesn’t mean there are no mosquitoes.

“Some of the most significant West Nile outbreaks have happened without significant rainfall,” says Dr. Justin Talley, Head of Entomology and Plant Pathology at Oklahoma State University. “Just because you don’t see water doesn’t mean there are no breeding areas around.”

He shared four tips for protecting horses from West Nile Virus. The first is to vaccinate your horses. Number two is hanging high-powered livestock fans. Third, get rid of as much standing water as possible and clean the horses’ water sources once a week.

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Mosquito control district rolling out sprayer on wheels capable of potent, ultra-fine mist

From KGET
June 1, 2022

BAKERSFIELD, Calif. (KGET) – Kern County’s ongoing battle against disease-carrying mosquitoes has a new weapon. A truck-mounted sprayer that’s capable of producing a super-fine, super-effective mist is coming to a neighborhood near you.

It’s called a Wide Area Larvicide Spraying system, and it will specifically target ankle-biters, or as they’re more formally known, Aedes aegypti. Those are the persistent bugs that showed up in Arvin in 2013, made their way to Bakersfield in 2018 and haven’t left since then.

They’re not just annoying – they can carry West Nile Virus. Starting June 6, the Kern Mosquito and Vector Control District’s new spraying system – WILS for short – will embark on a six-week pilot project. But you’re not invited to watch, even if you’re tempted by the rather noisy motor.

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West Nile Virus detected in Davis

From Fox 40
May 31, 2022

DAVIS, Calif (KTXL) — A dead American Crow collected in Davis was found to be carrying West Nile Virus by the Sacramento-Yolo Mosquito and Vector Control on Tuesday, according to vector control.

This is the first sign of West Nile Virus activity in the Sacramento area this year, according to vector control.

“Finding the first positive bird is always significant because it provides an early warning sign for the disease,” District Manager Gary Goodman said. “It confirms that the virus is present, provides a good indication of where we may find positive mosquito samples and where human cases may develop later in the season”

According to vector control, this is not the first sign of the virus in California as other counties have already seen activity of the virus.

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Dead bird found in Davis with West Nile virus, Sacramento-Yolo mosquito control confirms

From the Sacramento Bee
May 31, 2022

Summer has not yet begun, but the Sacramento-Yolo Mosquito and Vector Control District confirmed Tuesday that they already have found one bird that has tested positive for West Nile virus.

“Finding the first positive bird is always significant because it provides an early warning sign for the disease,” said District Manager Gary Goodman. “It confirms that the virus is present, provides a good indication of where we may find positive mosquito samples and where human cases may develop later in the season,”

Found in Davis, the bird is an American crow and is the second West Nile-positive bird discovered statewide this year. Vector districts in Contra Costa, Fresno, Kern, Orange and Riverside counties already have confirmed West Nile activity in mosquito samples, according to the westnile.ca.gov website. Contra Costa officials reported the first dead bird with the virus statewide on May 17 — it was found in an area of Brentwood close to Discovery Bay.

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Kern Mosquito enlists new weapon in fight against ‘ankle-biters’

From Bakersfield.com
May 31, 2022

Aedes aegypti, known in some areas of the world as the yellow fever mosquito — but known locally as “ankle-biter” — made its debut in greater Bakersfield in 2013.

At that time its numbers were quite low.

“Now they’re everywhere,” said Phurchhoki Sherpa, scientific program director for Kern Mosquito & Vector Control District, the special district charged with controlling mosquito populations in the southern valley.

Beginning next week, the district will try out a new strategy in limited areas in Bakersfield — and if it is successful, the project will likely be expanded.

The plan required some new equipment for the district.

“This is a truck-mounted A1 Super Duty mist blower, and its general purpose is to produce a fine mist that will be blown up into the air,” the district’s public information officer Terry Knight said Tuesday.

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Just when you thought you were safe from virus… here come the skeeters.

From the Sonoma County Gazette
May 27, 2022

The Marin/Sonoma Mosquito and Vector Control District is reminding residents to pack mosquito repellent when preparing for outdoor activities this Memorial Day weekend. “The holiday weekend is a time when many residents spend time outdoors,” stated Nizza Sequeira, Public Information Officer for the Marin/Sonoma Mosquito and Vector Control District. “Protection against mosquito bites and mosquito-borne diseases is imperative, especially at dusk and dawn. Personal protection measures include wearing long sleeves and long pants, and applying an effective insect repellent to exposed skin,” said Sequeira

While West Nile virus is endemic to the area, District officials say it has not yet been detected in Marin and Sonoma counties this year. West Nile virus activity has been detected in other areas of California, though, so residents should be extra vigilant about protecting themselves from mosquito bites when traveling to other areas.

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mRNA vaccination induces tick resistance and prevents transmission of the Lyme disease agent

Posted by Vector and Vector-borne Disease Committee
May 26, 2022

ANDALEEB SAJID [HTTPS://ORCID.ORG/0000-0001-6248-4985], AQUELINE MATIAS, GUNJAN ARORA, CHEYNE KUROKAWA, KATHLEEN DEPONT, EXIAOTIAN TANG, et al. 

SCIENCE TRANSLATIONAL MEDICINE [17 Nov 21], Vol 13 [620], <DOI: 10.1126/scitranslmed.abj9827>

Summary [Journal].  Repeated exposures to the black-legged tick, Ixodes scapularis, can lead to acquired resistance against ticks or “tick immunity.” To generate tick resistance, the authors developed an mRNA vaccine that encoded for 19 I. scapularis salivary proteins (19ISP). Guinea pigs vaccinated with 19ISP developed erythema at the site of tick attachment, a feature of acquired tick resistance. This led to poor tick feeding and, in the case of ticks infected with the Lyme disease agent, Borrelia burgdorferi, reduced transmission of the pathogen. Thus, 19ISP is a promising candidate for antitick vaccines that may also prevent transmission of tick-borne spirochetes.

Comment:  The relatively long attachment of ticks on the host during feeding have made them a frequent target for accine development.  In the 1990s, anti-tick vaccines were developed and marketed in Australia against cattle ticks [See A.E. Tabor. 2021. https://doi.org/10.3390%2Fvaccines9091030], but problems with dosing led to disuse.  No anti-tick vaccines have been approved for humans.    

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Prevalence of filarial parasites in field-caught mosquitoes in northwestern California

Posted by Vector and Vector-borne Disease Committee
May 26, 2022

Tiffany D. Tran,1 Brittany M. Nelms,2 Michelle L. Koschik,2 Jamesina J. Scott,2 Tara Thiemann1

1University of the Pacific, Biological Sciences, Stockton, CA 95211, U.S.A.

2Lake County Vector Control District, 410 Esplanade St., Lakeport, CA 95453, U.S.A.

Abstract [paraphrased].  Mosquitoes collected in Lake County, CA, in 2014 were tested for filarial parasite DNA using standard PCR. Filarial parasites were detected in 23 out of 1,008 total pools. Dirofilaria immitis, dog heartworm, was detected in Aedes increpitus (MIR=4.62), Aedes sierrensis (MIR=6.72), Anopheles freeborni (MIR=1.08), and Culex tarsalis (MIR=0.10). Setaria yehi, deer body worm, was detected in Ae. sierrensis (MIR=13.42), Anopheles franciscanus (MIR=0.55), An. freeborni (MIR=2.69), and Culex stigmatosoma (MIR=0.41). The avian parasite Splendidofilaria could not be identified to species but was detected in Cx. tarsalis (MIR=0.20). DNA was also detected for three unidentified filarial parasites in Culex.

Comment:  This research confirms that Aedes sierrensis is an important vector of dog heartworm, but indicates that previous studies using dissection techniques most likely over estimated infection rates that were confounded because of frequent infection with deer body worm.  Further research is needed to elucidate the vector competence of these naturally infected species. 

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Trypanosoma cruzi and Other Vector-Borne Infections in Shelter Dogs in Two Counties of Oklahoma, United States.

Posted by Vector and Vector-borne Disease Committee
May 19, 2022

Trypanosoma cruzi and Other Vector-Borne Infections in Shelter Dogs in Two Counties of Oklahoma, United States.

Kelly E. Allen and Megan W. Lineberry

Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, Oklahoma, USA.

VECTOR-BORNE AND ZOONOTIC DISEASES, Volume 22 (5), 2022.  DOI: 10.1089/vbz.2021.0078

Abstract [condensed]

Trypanosoma cruzi is an emerging zoonotic vector-borne parasite infecting dogs and other mammals in the United States. In this study we evaluated shelter dogs in one northeastern and one southeastern county in Oklahoma for prevalence of exposure and infection with T. cruzi using the Chagas STAT PAKassay and PCR, respectively.  Overall, 26 of 197 (13.2%) shelter dogs had detectable antibodies against T. cruzi and 3 of 189 (1.6%) dogs were PCR positive.   In addition, the dogs were tested for evidence of infection with other vector-borne organisms using the SNAP 4Dx Plus Test and PCR and  42  (21.3%) had evidence of exposure to or were infected with at least one other vector-borne agent including Anaplasma phagocytophilum,Anaplasma platys, Babesia sp. (Coco), Dirofilaria immitis, Ehrlichia canis, Ehrlichia chaffeensis,Ehrlichia ewingii, and Hepatozoon americanum. This study serves to boost state-wide veterinary and public health awareness vector-borne pathogens infecting shelter dogs in Oklahoma.

Note:  This study shows the importance of a One Health approach in detecting the presence of zoonotic pathogens by testing companion animals.  As pointed out in the recent MVCAC annual meeting, T. cruzi and vectors are found in California as well as some of the other tick-borne pathogens detected in this study. 

Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies

Posted by Vector and Vector-borne Disease Committee
May 19, 2022

Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies

Jonas Naslund,1 Clas Ahlm,2,3 Koushikul Islam,2 Magnus Evander,2,3,I, Goran Bucht,2 and Olivia Wesula Lwande2,3

1Swedish Defence Research Agency, CBRN, Defence and Security, Umea°, Sweden.

2Department of Clinical Microbiology, Umea° University, Umea, Sweden.

3Arctic Research Centre at Umea° University, Umea, Sweden.

iORCID ID (https://orcid.org/0000-0001-6034-4807).

VECTOR-BORNE AND ZOONOTIC DISEASES,  Volume 21(10) 2021

DOI: 10.1089/vbz.2020.2762

Abstract [condensed]

Emerging mosquito-borne viruses continue to cause serious health problems and economic burden among billions of people living in and near the tropical belt of the world. The highly invasive mosquito species Aedes aegypti and Aedes albopictus have successively invaded and expanded their presence as key vectors of Chikungunya, dengue, yellow fever, and Zika viruses leading to frequent local outbreaks and infrequent pandemics.  These two mosquito species have gradually adapted to new temperate ecozones inhabited by immunologically naive human populations. Many risk factors, for example, global transportation systems, may result in sporadic local outbreaks. There is an urgent need for improved surveillance of vector populations, human cases, and reliable prediction models. In summary, we recommend new and innovative strategies for the prevention of these types of infections.

Note:  This paper reviews recent Aedes related arbovirus outbreaks and describes their public health and economic impact.  This review clearly supports the need for surveillance and control programs to recognize and mitigate these imported arboviruses – problems addressed daily by the membership of the MVCAC. 

West Nile virus is back in Contra Costa County

From KRON4
May 17, 2022

BRENTWOOD, Calif. (BCN) – The first case of the year was found recently in a dead American crow in Brentwood, according to the Contra Costa Mosquito & Vector Control District. 

Since 2005, 75 people in Contra Costa have been diagnosed with West Nile virus. Two people died from the disease in 2006. The district said in a press release, “Certain birds carry WNV. Once a mosquito bites an infected bird, the mosquito can become infected. Mosquitoes can spread the virus when they bite another bird or person.” 

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How to protect yourself against mosquitoes possibly carrying diseases during SoCal summer months

From ABC 7
May 13, 2022

WEST COVINA, Calif. (KABC) — It’s a big problem that comes with warmer weather — more insects. Many, especially mosquitoes, can carry some very serious diseases.

The San Gabriel Valley is working hard to control pests there.

Levy Sun with the San Gabriel Valley Mosquito and Vector Control District says SoCal residents don’t stand a biting chance against mosquitoes this summer, and reports record numbers of the annoying insects.

“If you’re hearing buzzing, it’s definitely not in your head,” Sun said. “There really are more insects and mosquitos out there right now.”

The department warns the Culex, native to SoCal, is the mosquito responsible for spreading West Nile virus, and is known to bite closer to sunset. And a newer, invasive mosquito called Aedes, or ankle biters, bite aggressively during the day.

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As warm weather arrives, so does mosquito season

From the Antelope Valley Press
May 12, 2022

As warmer temperatures start and summer approaches in the Antelope Valley, residents are reminded that the change in the weather also means the beginning of mosquito season.

Of particular concern is an invasive species known to carry tropical diseases, a population that saw a tenfold increase in the Antelope Valley, last year, according to Antelope Valley Mosquito and Vector Control District officials.

The Aedes mosquito is not native to the area but was first found here, in October 2018. The mosquitos are known to carry different diseases than our native mosquitos, including yellow fever (they are sometimes known as yellow fever mosquitos), dengue fever, chikungunya and zika virus, according to officials.

None of these diseases have yet been found in the Antelope Valley or California.

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West Nile Virus confirmed in mosquitoes collected in Fresno County

From ABC 30
May 11, 2022

FRESNO, Calif. (KFSN) — Mosquito season is here. This means the West Nile Virus could be buzzing in your backyard.

“So this year, it’s a little early,” says Katherine Ramirez with the Consolidated Mosquito Abatement District. “We typically see positive mosquitoes in June.”

On Wednesday, the Fresno Mosquito and Vector Control District notified the Fresno County Department of Public Health of positive West Nile Virus cases collected in adult mosquitoes in Southeast Fresno.

While the Central Valley can be dry, Ramirez says any area in the Valley that has standing water can produce the potential for West Nile Virus-positive mosquitoes.

Ramirez advises folks to clean out or empty any standing water, including pools, the bottom of your plants and don’t forget to cover your yard drains.

West Nile can be a very serious illness and it only takes one bite to get sick.

Because there is no medication, health officials say prevention is key.

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West Nile Virus and Eastern Equine Encephalitis Virus High Probability Habitat Identification for the Selection of Sentinel Chicken Surveillance Sites in Florida

Posted by Vector and Vector-borne Disease Committee
May 9, 2022

West Nile Virus and Eastern Equine Encephalitis Virus High Probability Habitat Identification for the Selection of Sentinel Chicken Surveillance Sites in Florida

Sean P. Beeman1; Joni A. Downs2; Thomas R. Unnasch1; Robert S. Unnasch1

1Center for Global Health Infectious Disease Research, University of South Florida, 3720 Spectrum Boulevard, Tampa, FL 33612.

2School of Geosciences, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620.

J Am Mosq Control Assoc (2022) 38 (1): 1–6.

https://doi.org/10.2987/21-7049

ABSTRACT [partial].  Identifying high probability locations for WNV and EEEV transmission and relocating coops to areas of higher arbovirus activity would improve the sensitivity of the sentinel chicken surveillance program. Using 2 existing models, this study conducted an overlay analysis to identify areas with high probability habitats for both WNV and EEEV activity. This analysis identified approximately 7,800 km2 (about 4.5% of the state) as high probability habitat for supporting both WNV and EEEV transmission. Mosquito control programs can use the map resulting from this analysis to improve their sentinel chicken surveillance programs, increase the probability of virus detection, reduce operational costs, and allow for a faster, targeted response to virus detection.

Note:  Because the number of locations sampled by sentinel chicken flocks always is limited by resources, sentinel programs should utilize a ‘best estimate’ approach with birds positioned in areas with a consistent history of enzootic virus activity to enhance the probability of seroconversions and therefore sensitivity.   Focal studies in the Coachella Valley (Reisen et al. 1995) similarly found that the incidence of seroconversions in sentinel chickens were dependent upon flock location and the frequency of serum collection. 

Reference List

Reisen, W. K., H. D. Lothrop, S. B. Presser, M. M. Milby, J. L. Hardy, W. J. Wargo, and R. W. Emmons. 1995. Landscape ecology of arboviruses in southern California: temporal and spatial patterns of vector and virus activity in Coachella Valley, 1990-1992.  J. Med. Entomol. 32: 255-266.

West Nile Virus Information for Physicians

From CDPH VBDS
May 5, 2022

West Nile virus (WNV) has been detected in many regions of the state. Physicians should:

  • Be aware if WNV is active in their area
  • Look for symptoms of WNV
  • Test for WNV because testing:
    • differentiates WNV from other conditions (enterovirus, other arboviral diseases) and thus may prompt a change in treatment regime
    • results offer anticipatory guidance–both WNV neuroinvasive disease and WN fever patients can have lingering symptoms and knowing the underlying etiology is helpful for the patient and family members
    • helps mosquito control and public health agencies institute proper control measures to reduce the risk of further cases in the event of a positive result
  • Contact their local public health department for details on sample submission and testing

For additional information, please see these resources:

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Aerial surveillance begins Monday for mosquito ‘backyard breeders’

From Action News Now
May 5, 2022

BUTTE COUNTY, Calif. – The Butte County Mosquito and Vector Control District will be checking unmaintained swimming pools and other “backyard breeders” through aerial surveillance on Monday.

Matt Ball, District Manager of Butte County Mosquito and Vector Control District, says it’s critical to check these areas early in the mosquito season when the West Nile virus is most active. Ball says it could prevent larger populations from hatching in urban areas later in the year.

“Undoubtedly the number of human cases could have been far worse in the state last year if it had not been for this program and others like it,” Ball said.

The Butte County Sheriff’s Office helicopter will assist with most of the flight during the project.

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Fight against mosquito bites with these simple tips

From the Fresno Bee
May 5, 2022

Kern County sees return of mosquito season

From KGET
April 21, 2022

BAKERSFIELD, Calif. (KGET) — Local experts say mosquito season is in full swing, and it will last until October or November. The Kern County Mosquito and Vector Control District says ankle-biting mosquitoes are back, but you can take steps today to keep them away from your home. Experts say a small, black-and-white mosquito called the Aedes Aegypti is already buzzing around Kern County.

“It’s a mosquito that not only will bite you multiple times, but it will bite you in the daytime,” said Terry Knight, of the Kern county Mosquito and Vector Control District. “It’s breeding in our front yards and our backyards. It’s going to be back, because we’re already seeing early numbers of this mosquito right now.”

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Bacteria-Carrying Mosquitoes Can Protect People From Dengue. New Study Reveals How

From APB Live
April 20, 2022

New Delhi: Dengue is the most widespread mosquito-borne disease in the world, and is caused by dengue viruses, which is spread to people through the bite of an infected Aedes species (Aedes aegypti or Aedes albopictus). These mosquitoes also spread Zika, chikungunya, and other viruses, according to the Centers for Disease Control and Prevention (CDC). The transmission of dengue between humans is mediated by the bites of female Aedes aegypti mosquitoes.

About four billion people in the world live in areas with a risk of dengue. About 400 million people get infected with dengue each year. To date, there are no medical treatments for people suffering from this disease. 

The dengue virus causes symptoms ranging from high fevers to severe bleeding and shock, and can be life-threatening. Most common symptom of dengue is fever with nausea, vomiting, rash, or aches in the eyes, muscles, or joints. The disease presents an enormous burden on health systems. 

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Ventura County Officials Warn It’s Mosquito Season

From KVTA
April 19, 2022

his is Mosquito Awareness Week and Ventura County Environmental Health officials are reminding us to take actions aimed at protecting ourselves and others from being bitten by mosquitos and also eliminating conditions that allow them to breed.

     They say make sure there is nothing in your yard that could collect even small amounts of water that can be used by mosquitos to breed.

     As far as avoiding being bitten, make sure you make it hard to allow mosquitos to enter your residence and wear protective clothing like long sleeve shirts and long pants.

     Also use EPA approved insect repellant.

     Mosquitos can transmit several diseases including West Nile Virus. 

     Below is the news release from Ventura County Environmental Health with more details…

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Researchers develop chemical-free, mosquito-proof clothing to help prevent bites

From 23 ABC
April 19, 2022

Mosquito bites are not pleasant.

“It takes and wiggles that mouth pore through the threads in your clothing,” Michael Roe, a professor at the North Carolina State University Department of Entomology and Plant Pathology, said.

And sometimes, even a shirt can’t prevent them from getting to you. ”They can bite through animal fur, they can bite through your clothing,” Roe said.

But, at this lab, Roe and his team are developing something to change that, using mosquitos they raise in-house.

“We’ve been able to develop a series of parameters that every textile has, and by having the right combination of those parameters you can prevent a mosquito from biting through that textile,” he explained.

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Vector Control District Celebrates Seven Decades of Working to Rid the County of Mosquitos

From the Culver City Observer
April 14, 2022

To celebrate the 70th anniversary of providing public health service, the Greater Los Angeles County Vector Control District (District) will host an open house at its Santa Fe Springs Headquarters on Saturday, April 16th from 10am to 2pm. For seven decades, the District has protected cities and communities from mosquito-borne diseases through surveillance, mosquito control, and public health education.

The free event is open to the public and will have food, music, activities for the whole family, and giveaways. The open house celebration is an opportunity for cities, elected officials, community partners, and residents to meet staff, learn about mosquito control, and explore the District’s facilities.

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VBDN Meets With Congressional Staff to Discuss PREVENT Pandemics Act

From Entomological Society of America Science Policy News
April 11, 2022

The Vector-Borne Disease Network (VBDN), a stakeholder group of nonprofit organizations including membership and trade associations, vector control groups, and educational institutions such as the Centers for Disease Control and Prevention Regional Centers of Excellence [Note: the PacVec Center is directed by faculty at UC Davis and Riverside], convened online as a group for the first quarterly meeting of the year on March 21. The VBDN invited Senate Health, Education, Labor, and Pensions (HELP) Committee majority and minority staff as special guests to speak to the group about S.3799, the “Prepare for and Respond to Existing Viruses, Emerging New Threats, and Pandemics Act” (PREVENT Pandemics Act), and ways the VBDN can help support their efforts.

While the bill is very broad in terms of public health priorities, specific to the interests of the VBDN are provisions that support biosurveillance, genome sequencing, a new epidemic forecasting center, loan forgiveness for public health professionals including vector management professionals (a program that has been authorized but unfunded previously), a new advisory committee to help improve communications during a public health emergency, a One Health Framework, and other ways to incentivize new talent in public health.

Impact of COVID-19 on the Vector-Borne Disease Research and Applied Public Health Workforce in the United States

Caroline T. Weldon1Scott C. Weaver1, and Kathryn H. Jacobsen2

Western Gulf Center of Excellence for Vector-Borne Diseases and Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas; 

 University of Richmond, Richmond, Virginia

Am. J. Trop. Med. Hyg.  106: 1003-1004.  DOI: https://doi.org/10.4269/ajtmh.21-1340

Summary:  The COVID19 pandemic has caused major disruptions to medical and public health research productivity, especially among laboratory researchers.   These applied and academic public health workforce challenges have had a significant adverse impact on vector-borne disease (VBD) work in the United States over the past 2 years.   Based on responders to a small convenience survey, the authors observed the following trends:  1) Early in the pandemic, VBD personnel reported disruptions to the acquisition of biological specimens and laboratory equipment and supplies.  2) Much of the VBD workforce in 2020 were re-assigned to COVID-19 contact tracing and efforts on VBDs were reduced. 3) During 2020 and 2021 there was concern that VBDs were underdiagnosed and underreported, thereby reducing funding and resources for emerging VBDs.  4)  The responders felt that it will take several years for VBD research to regain momentum creating a decrease in publications reflecting the void in research.   

“We’re at a critical point in the fight against malaria”

From the World Health Organization
April 7, 2022

In the lead-up to World Malaria Day 2022, we spoke with Dr Audrey Lenhart, Chief of the Entomology Branch in the Division of Parasitic Diseases and Malaria at the US Centers for Disease Control and Prevention (CDC) and incoming co-chair of WHO’s Vector Control Advisory Group (VCAG), about where we are in the global fight against malaria, some of the new innovations being developed to help manage the mosquitoes spreading the disease, and the role of VCAG in both expediting and assessing new technologies for WHO. This conversation has been lightly edited for concision and clarity.

Thanks for taking the time to talk today. First, could you tell us a little about your own background in malaria prevention and how you came to be a part of VCAG?

Sure. Before joining VCAG and even CDC, my background was more focused on Aedes aegypti control [the mosquito that transmits arboviral diseases such as Zika, dengue, chikungunya, and yellow fever] and insecticide resistance. Then when I joined CDC about 10 years ago, my work became much more focused on malaria.

I believe I was initially invited to participate in VCAG because I had experience with both Aedes control and malaria vector control, as well as experience in conducting large field trials of vector control tools with both entomological and epidemiological outcomes. That latter experience aligned particularly well with VCAG’s role in providing feedback to applicants on vector control trial design, and specifically around building a strong evidence base for understanding the public health impact of vector control tools.

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Crane fly or mosquito eater? Here are a few things you might not know about this common insect

From Recordnet.com
April 7, 2022

Crane flies, we’ve all seen them awkwardly bumping into walls, ceilings and windows, gathered around porch lights or stuck to your window screens. In our area, they commonly known as mosquito hawks or mosquito eaters, but did you know, they don’t actually eat mosquitoes.

Adult crane flies spend their very short lives with only love on their tiny minds. The sole purpose of the adult crane fly is to mate and, for the females, to lay eggs for next spring’s crop of flies. The adults don’t really eat at all but, they are undoubtedly greatly appreciated by hungry birds at this time of year, as well as smaller mammals, fish, spiders and predatory insects. Crane flies are harmless to handle, so the next time one makes its way indoors, simply cup it gently to release outdoors.  

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Drain standing water to prevent mosquito breeding

From the Winters Express
April 7, 2022

The recent rain, combined with warm temperatures in the days ahead, make for the perfect breeding ground for mosquitos.

That’s why the Sacramento-Yolo Mosquito and Vector Control District is urging everyone to “drain the rain” to protect against mosquito-borne illnesses.

“Mosquitoes complete their life cycle much faster in warm weather,” said district manager Gary Goodman. “We urge all residents to do their part and help us drain standing water from common backyard sources such as buckets, flower pots, bird baths, old tires and other small containers that may breed mosquitoes.

“Getting rid of areas where mosquitoes can breed now will go a long way later in the season,” he added.

This is especially important for the prevention of invasive mosquitoes which have been rapidly spreading throughout the district since 2019.

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As Severe Drought Conditions Increase, So Does Percentage of Local Mosquitoes Carrying West Nile Virus

From Pasadena Now
April 4, 2022

Extreme drought conditions have been prevalent across the San Gabriel Valley for years and now new research suggests that as the drought intensifies, the percentage of infected West Nile mosquitoes goes up.

A steady rise in infected mosquitoes in the Pasadena area has been documented since 2019.

Data provided by San Gabriel Valley Mosquito and Vector Control District (SGVMVCD) revealed that a total of 17 mosquito samples from San Gabriel Valley tested positive for WNV in 2019, 53 samples tested positive in 2020 while 190 samples tested positive in 2021.

This counterintuitive relationship between less water and more West Nile virus-carrying mosquitoes was described in 2017 by scientists who studied the relationship between climate change and the virus.

One of them, Sara Paull, a disease ecologist at the National Ecological Observatory Network in Boulder, Colorado, told Kaiser Health News the connection may have to do with birds.

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