West Nile Virus
Prevalence: High
Risk 3/5
Western Encephalitis Mosquito
Culex tarsalis · “The Western Vector”
Medium brown mosquito found primarily in western US. Important vector for encephalitis viruses. Breeds in clear water.
Disease risks
Western Equine Encephalitis (WEE)
Prevalence: Moderate
St. Louis Encephalitis
Prevalence: Moderate
How to identify
- Size
- 5-7mm (medium)
- Color
- Brown with lighter markings
- Distinctive features
- Distinctive tarsal (leg) markings; palps shorter than proboscis
- Resting posture
- Head-up posture
- Prefers
- Mammals and birds
- Pain level
- Moderate
- Persistence
- Moderate
- Transmission
- Important vector for encephalitis viruses in western US
What actually works
Habitat Elimination (Source Control)
Removal and treatment of breeding sites. Professional inspection identifies and eliminates standing water where mosquitoes lay eggs.
Drain & Catch Basin Treatment
Professional treatment of storm drains and catch basins where Culex mosquitoes breed. Licensed technician application with long-lasting IGR.
Pyrethroid Spray Treatment
Professional-grade synthetic pyrethroid insecticide applied by licensed technicians. Fast-acting, EPA-approved, effective against adult mosquitoes.
Cities where Western Encephalitis Mosquito is active
Los Angeles, CaliforniaPhoenix, ArizonaSan Diego, CaliforniaSan Jose, CaliforniaSan Francisco, CaliforniaLas Vegas, NevadaTucson, ArizonaFresno, CaliforniaSacramento, CaliforniaMesa, ArizonaLong Beach, CaliforniaOakland, CaliforniaBakersfield, CaliforniaAnaheim, CaliforniaStockton, CaliforniaHenderson, NevadaRiverside, CaliforniaSanta Ana, California
Fun fact
Culex tarsalis is the primary West Nile Virus vector in the western United States and is particularly active during late summer months.