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11.4.13: As the season winds down, the District is working hard to suppress next year's Asian tiger mosquito population by breaking the mosquito life cycle this fall and prevent the spread of this mosquito.  We will conduct an additional treatment along the northern edge of the infestation on *REVISED DATE* Thursday November 7 between the hours of 12 a.m. and 5 a.m. And Friday, November 8 between the hours of 12 a.m. and 5 a.m. (as needed) Details can be found here

10.16.18: District staff will conduct an additional treatment for Asian tiger mosquitoes at the northern edge of the infestation in portions of southern Arcadia and unincorporated Los Angeles County on Friday 10/18/13 between the hours of 1:00 a.m. and 3:00 a.m.  A map of the treatment area can be seen at: and details are available here.

8.27.13: Our next treatment will occur during the early morning hours (midnight to approx. 5AM) on Wednesday August 28th in the infestation zone in El Monte.  The treatment areas can be seen at  The District will apply Altosid (S-Methoprene) as a ultra-low volume fog targeting immature mosquitoes in backyard water-filled containers. Click for details.

8.16.13: Additional treatments are scheduled for early Tuesday, August 20, 2013 between the hours of 12AM (midnight) and 5AM in the following area: Area 1 is scheduled for treatment (area 2 if time permits). Details can be found here.

8.13.13: The District will treat several neighborhoods for adult Asian tiger mosquitoes during the early morning hours of August 15th.  Neighborhoods scheduled for treatment can be seen at:  Complete details can be found here

6.24.13 UPDATE: We continue to see tiger mosquito activity. To address the ongoing infestation,  we have scheduled an additional treatment targeting immature (larval) mosquitoes for the early morning hours of Thursday June 27th in select neighborhoods in El Monte and South El Monte.  To view the treatment area visit and read our press release.

4.9.13 UPDATE:  In partnership with the Greater Los Angeles County Vector Control District, we will conduct our first large-scale treatment for Asian tiger mosquitoes on April 11, 2013 during the overnight hours between 12am and 5am. Targeting the immature mosquitoes in the early season will suppress adult populations as the season progresses.  Read our latest Press Release for more information on treatment areas, products used, and what you can do to help!   

11.5.12 UPDATE:  Asian tiger mosquito activity in October was the highest level seen to date.  A total of 92 samples were collected in October from the cities of El Monte and the southern edge of Arcadia.  As mosquito activity winds down for winter, it is imperative that residents search for and remove all containers that may fill with water during the rainy season.  Female tiger mosquitoes will lay eggs on these containers that will hatch next spring. LET'S BREAK THIS CYCLE TODAY!    

10.10.12 UPDATE: Tiger mosquitoes were identified for the first time in the City of Arcadia - approximately 1/4 mile northeast of the intersection of Santa Anita and Live Oak Avenues, along the city's southern border.  We urge residents in this area, and throughout the infestation zone,  to immediately remove all containers that can capture and hold rainwater before the rain expected tonight.  

9.20.12 UPDATE: Asian tiger mosquitoes have been found on more than 240 properties in the El Monte and South El Monte area this year alone.  Read the latest press release.

Our goal is to eradicate this mosquito, but we cannot do it without your help.  

Read the latest press release and help us protect your community!

Download the Infestation Alert Flyer in English, Spanish, or Chinese and share with your neighbors and family!

WATCH OUR NEW VECTOR INSPECTORS ANIMATED SHORT FOR KIDS! Would you like a kit of your own? OR a class setContact us!

VECTOR INSPECTORS animated video wins awards!  Check it out:


The Asian tiger mosquito (Aedes albopictus) was identified September 2, 2011 in the City of El Monte.  This aggressive day-biting mosquito is very small (approx. 1/4 inch) with distinctive black and white banding.  If you think you have seen this mosquito or have received mosquito bites during daylight hours, please REPORT them and help us eliminate this threat.  

The Asian tiger mosquito survives well in association with humans and lays eggs in smaller water-filled containers around the property. 

  • Dump out standing water and store containers upside down
  • Dispose of or remove any unused containers
  • Dispose of tires stored outdoors or move them to a sheltered area
  • Drill drain holes in the bottom of tire swings or other play equipment that may collect rainwater

Expanded Search Continues

The District is working with the Greater Los Angeles County Vector Control District to inspect other areas to determine the extent of the infestation.  The interactive map below shows streets highlighted in BLUE where the Asian tiger mosquito has been identified to date. 

As of November 8, 2011, the Asian tiger mosquito has been found in the cities of El Monte and South El Monte and in a County area near the border of Duarte and Irwindale.  

Managing this species will require ongoing, aggressive actions to eliminate standing water on both public and private property.  This mosquito lays its eggs above the waterline in small containers (such as saucers under potted plants) which are holding or have recently held water.  Empty all containers and place them in the sun for 24-48 hours before storing inverted to kill any eggs present and help break the mosquitoes lifecycle. 

We need the public's help! Please check your yard carefully for anything that may collect and hold rainwater - search under bushes for cans, bottles, toys, or other objects and dispose of, or store these indoors or in a covered area. 

Even though it is winter, we are still seeing mosquito activity.  The work we do NOW will reduce the number of mosquitoes surviving and reproducing next spring!


For More Information:

National Pesticide Information Center: Pesticides used in mosquito control

University of California, Riverside Center of Invasive Species Research  

Centers for Disease Control and Prevention - Aedes albopictus information


West Nile Virus is present in the San Gabriel Valley EVERY year!

Please take a few minutes to walk around your property and dump out any accumulated rainwater from buckets, barrels, old tires, etc.  The work you do now will break the mosquito life cycle and protect you and your family from West Nile virus!

Contact the District to report 'green' inoperable swimming pools or non-functional ponds & fountains.  These can breed thousands of mosquitoes each week.

WNV is primarily transmitted bird to bird by mosquitoes.  Many species of birds can get WNV and in some, it is nearly always fatal.  The presence of dead birds in the neighborhood is often the first indication of WNV activity. 

Help us monitor and control WNV - Report ALL DEAD BIRDS to or (877) 968-2473.  Not all birds can be collected and tested.  These reports help us direct our control efforts and keep you safe.

Good information about the symptoms and illness due to WNV can be found at


Information on transmission, surveillance, symptoms, and recommended precautions.

8.27.13 UPDATE: West Nile virus activity has increased in the San Gabriel Valley - Infected mosquitoes and chickens tested positive last week from the following cities: Arcadia, Irwindale, and Monterey Park. Residents should assume WNV is being actively transmitted by mosquitoes throughout the San Gabriel Valley and take necessary precautions to avoid mosquito bites. Read our latest press release.

8.7.13 UPDATE: The District received confirmation of additional WNV infection in birds in the San Gabriel Valley.  View the table below for the latest information. This is clear indication that the virus is active and transmitting - take precautions to protect yourself and your family.

6.6.13 UPDATE:  First incidence if West Nile virus found this year in San Gabriel Valley.  A dead bird picked up from the city of Arcadia tested positive for WNV.  It's time to check your yards and dump out water in buckets, saucers, or any other containers now to break the mosquito live cycle.  Information about other activity in California can be found at


The District tests dead birds, chickens, and mosquitoes for the presence of mosquito-transmitted virus.  More information can be found on our Disease Surveillance tab

So far this year, West Nile virus has been detected in the following cities:

Dead Birds Dead Birds Mosquitoes Chickens
Arcadia 4 1 4
Azusa 1    
Claremont 1   1
Covina 8    
El Monte 2    
Glendora 1    
Irwindale     3
La Verne 1    
Monrovia 2    
Monterey Park     1
San Gabriel 1    
West Covina 2    


Report standing water or request our assistance

Report dead birds

How to Control Mosquitoes

Check out our NEW Mosquitoes & Mosquito-Borne Disease Brochure

Are you seeing GIANT MOSQUITOES?


Every spring we receive numerous calls reporting an emergence of 'giant mosquitoes' that residents often find indoors or around porch lights.  The good news is that these are NOT mosquitoes and they are not dangerous. 


Crane flies are an important spring-time food source for baby birds, so if they make their way indoors, just capture them in a cup and release them back outside.  For more information read Crane Fly Facts  or visit: 


Important links regarding West Nile Virus:

General information - WNV Brochure PDF File

CDC WNV Website - Web Site 

State of California WNV Information - Web Site  

Los Angeles County WNV Website - Web Site 

West Nile virus information in Spanish - Web Site    PDF File

West Nile virus information in Chinese - Web Site  PDF File

West Nile virus information in Vietnamese -  Web Site 

Joint Statement on Mosquito Control in the United States from the U.S. Environmental Protection Agency (EPA) and the U.S. Centers for Disease Control and Prevention (CDC):

Maps & Current Case Information -

Press Releases:

All press releases are in .pdf format. If you do not have Adobe Acrobat installed, or have trouble viewing the files please click here to get the latest version of Acrobat.


9.13.13 - WNV Identified in Claremont

8.27.13 - WNV Activity Intensifies in San Gabriel Valley

8.27.13 - Treatment Scheduled for Asian Tiger Mosquitoes

8-16-13 - Treatment Scheduled for Asian Tiger Mosquito

8-12-13 - Fogging Scheduled in El Monte to Combat Asian Tiger Mosquitoes

7-08-13 - More WNV found in the San Gabriel Valley

6-24-13 - Joint Treatment for Tiger Mosquitoes Scheduled

6-6-13 -  West Nile virus Found in Arcadia

5-29-13 - Helicopter Surveillance for Green Pools Begins

4-09-13 - Early-Season Treatment to Target Asian Tiger Mosquitoes

10-9-12 - Asian Tiger Mosquitoes Found in Arcadia

9-20-12 - Asian Tiger Mosquito Update

8-31-12 - WNV Activity Intensifies in San Gabriel Valley

8-24-12 - WNV Detected in Monrovia Mosquitoes

8-16-12 - Heat and Humidity Increase Mosquito Dangers

7-18-12 - More WNV Found in San Gabriel Valley

7-03-12 - Additional Fogging Scheduled to Combat Asian Tiger Mosquito Infestation

6-21-12 - Treatment for Adult Tiger Mosquitoes Scheduled for Friday

6-18-12 - Increase in Tiger Mosquitoes in El Monte

5-14-12 - Tiger Mosquitoes Confirmed in El Monte and South El Monte

3-15-12 - Invasive Tiger Mosquitoes: Are They Back?

11-30-11 - High Winds May Help Fight Invasive Mosquito

11-7-11 - Additional Door-to-Door Inspection Scheduled

10-2-11 - Multi-Agency Expanded Search

9-22-11 - UPDATE - Invasive Mosquito in San Gabriel Valley

9-12-11 - Invasive Mosquito Found in El Monte

8-22-11 - WNV Activity Continues - Public Participation Helpful

8-01-11 - West Nile Virus Risk Higher This Year

6-24-11 - More WNV Found - Neglected Pools May be to Blame

5-12-11 - Are you Neglecting Your Pool? We're Looking For You!

5-12-11 - West Nile Virus Found in San Gabriel Valley

8-20-10 - More WNV Found in San Gabriel Valley

7-02-10 - West Nile Virus Found in Covina Crow

4-27-10 - Canine Heartworm Risk Increased in San Gabriel Valley

7-23-09 - West Nile Virus Found in La Verne and La Puente Birds

5-21-09 - Day in the District - Open House May 29, 2009

9-10-08 - Mosquito Control Services Now Available to Baldwin Park Residents

8-28-08 - Risk of WNV Remains High - Stay Safe Over Labor Day Weekend

8-04-08 - Southern California Vector Control Districts Band Together to Fight WNV

7-09-08 - Elevated WNV Risk in Several San Gabriel Valley Cities

5-29-08 - First Identification of WNV in 2008 - Arcadia & Temple City Crows Test Positive

9-06-07 - Mosquitoes From San Gabriel Test Positive

9-04-07 - West Nile Found in West Covina Mosquitoes

8-30-07 - First Infected Mosquitoes Found in Covina

8-24-07 - Additional Birds Infected with WNV Detected

8-03-07 - West Nile Virus Detected in West Covina

6-26-07 - Battling West Nile Virus From the Air

3-08-07 - West Nile Virus Detected in El Monte Crow

2-16-07 - West Nile Virus Detected in Monterey Park

8-07-06 - KTLA Aids in West Nile Virus Fight

5-03-06 - Foothill Air Support Team and Vector Control Take to the Skies in Search for Green Swimming Pools

2-08-06 - District Hosts Open House

9-13-05 - Vector Control Aids in Hurricane Relief

7-21-05 - Vector Control to Ground Adulticide for mosquitoes

07-21-05 - New West Nile Virus Awareness insert available here

07-14-05 - Warming Trend Brings Increased Evidence of West Nile Virus in San Gabriel Valley

07-14-05 - West Nile Virus Identified in Valley

07-11-05 - Vector Control Needs the Public's help

5-31-05 - Pasadena Police Helicopters Join Fight Against West Nile Virus

01-21-05 - Mosquito Concerns on the Rise

08-05-04 - District Services Expand Due to West Nile Virus

07-22-04 - Additional Fogging at Arboretum Unnecessary

07-16-04 - Increased West Nile Activity Triggers Localized Fogging

04-21-04 - More West Nile virus Found in Southern California

04-01-04 - West Nile virus Resurfaces in San Gabriel Valley

09-15-03 - West Nile virus Found in Arcadia

06-19-03 - Hidden Dangers in Your Backyard

09-06-02 - State Health Director Announces Probable Case of West Nile Virus

06-28-02 - Mosquito & Vector Control Services Now Available to Altadena & Kinneloa Residents

06-12-02 - Emerging Diseases... Are we Prepared?

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1145 N. Azusa Canyon Road - West Covina, CA 91790 - 626.814.9466