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MOSQUITOES

OVERVIEW

Many people know the mosquito because of its annoying nature and its bothersome bites. Yet, often their dangerous nature is overlooked. Over 1 million people die from mosquito-borne diseases annually. Female mosquitoes can lay up to 300 eggs at a time and can do so up to three times until they die. Their existence is practically inevitable but there are many easy ways to keep yourself and your community safe. Aside from control and surveillance, the District strives to spread awareness about the danger of mosquitoes while educating the public on key ways to stay safe.

Life Cycle

LIFE CYCLE

In the United States, there are approximately 200 species of mosquitoes each with their own characteristics. Only about 12 of these are of public health concern. California has about 50 species, and only a few are a health threat. When developing, they go through the same four life stages but, depending on the type of mosquito, the cycle could be completed in as little as four days or it could last as long as one month. 

Adult

Egg

Larvae

Pupae

larva_edited.png
Adult Mosquito
pupa_edited.png
egg_edited.png

EXAMPLES OF BREEDING SITES

Breeding Sites

Mosquitoes need water to survive. Without a stagnant water source, some mosquitoes cannot lay their eggs and the eggs that are able to be laid in damp soil need to be flooded by water in order to hatch into larva. Eggs will not hatch without a water source. Below are a few examples of breeding sites that you might be able to find in your own backyard.

Pic of green pool
Pic of water in planter
pic of empty pots
cup with mosquito larvae

STANDING WATER

Vector Control Districts often recommend that water sit for no more than 48 hours.  Especially in the summer, water that sits for longer than 48 hours can have enough algae and bacteria to support mosquito larvae development and become an attractive place for female mosquitoes to lay their eggs. 

 

Items like trash cans and planter pots  can accumulate water and turn foul quickly and should be drained as quickly as possible. 

 

Birdbaths and pet watering dishes left outside should be monitored daily, checked for the presence of algae and organic matter that can foul the water, and cleaned weekly at minimum.

 

Ponds and water gardens should have the surface of the water agitated using a sprinkler or other pumping device, and if possible, mosquitofish (available at the District) can be added to remove larvae.

Vector Control Recommendations for Stormwater Best Management Practices

Best Choices

Source Control

Treatment Control

  • Efficient irrigation

  • Pervious pavements

  • Routine street sweeping

  • Routine drainage system maintenance

  • Minimize non-stormwater discharges

  • Vegetated swale

  • Infiltration trench

  • Infiltration chambers

  • Drain inserts

  • Bioretention

Avoid

Source Control

Treatment Control

  • Over irrigation of swales and basins

  • Conveyance pipes that hold water - nyloplast

  • Drywells that fluctuate with groundwater

  • Loading docks that hold water or have sumps

  • Hydrodynamic separators - CDS/ vortex

  • Baffle boxes

  • Media cartridge filters

  • Constructed wetlands/wet ponds

Incidence maps
Public Health Danger

PUBLIC HEALTH CONCERNS

According to the World Health Organization, more than 50 percent of the world's population is at risk from mosquito-borne diseases. Mosquitoes can transfer and transmit diseases, such as West Nile virus, to humans and they can cause sickness or sometimes even death​. Though not all bites transmit disease, they still become a nuisance to most due to the extreme itchiness and other possibly severe reactions caused by the saliva left behind after the mosquito bites. This could interfere with how often one wants to participate in outdoor activities and sports.

Mosquito landing on a hand

Typically, some mosquito-borne diseases stay within a certain geographical area, but through travel and other agents, diseases are capable of spreading into foreign regions. Here at the District, we survey mosquitoes by setting out traps to capture mosquitoes throughout our region. Then, we bring in the traps to check the amount of mosquitoes caught in those regions in order to assess which regions are having mosquito problems. After that, female mosquitoes undergo disease testing to see if they are carriers of any diseases, native or non-native. These diseases include:

CHIKUNGUNYA

DENGUE

WEST NILE VIRUS

YELLOW FEVER

ZIKA VIRUS

Click the links above to learn more about the diseases

Types of Mosquitoes

TYPES OF MOSQUITOES

Aedes GENUS

  • Breeding Habits: Female mosquitoes tend to lay their eggs in areas that become flooded.

  • Physical Attributes: Abdomen has a pointed tip.

  • Flying Abilities: Can travel up to 75 meters from breeding sites

  • Biting Habits: Typically bite mammals with a preference for humans

  • Activity Habits: Active mainly at dawn and early evening

  • Common Species in Southern California: Aedes aegypti, Aedes albopictus, Aedes sierrensis

  • Invasive Species: Aggressive day-time biters including Aedes aegypti (Yellow fever mosquito) and Aedes albopictus (Asian tiger mosquito). These mosquitoes have a limited flight range typically staying close to breeding sites.
     

Aedes mosquito
Anopheles mosquito

Ary Farajollahi, Bugwood.org 

Anopheles GENUS

  • Breeding Habits: Females mosquitoes tend to lay their eggs in permanent freshwater.

  • Physical Attributes: Abdomen has a pointed tip. Palps are as long as the proboscis. 

  • Flying Abilities: Cannot fly far from their breeding sites.

  • Biting Habits: Bite often with a preference for humans and other mammals.

  • Activity Habits: Usually active at dusk, dawn, and night

  • Common Species in Southern California: Anopheles hermsi (southern California malaria mosquito), Anopheles franciscanus

Culex GENUS

  • Breeding Habits: Female mosquitoes tend to lay their eggs in calm, stagnant water.

  • Physical Attributes: Abdomen has a blunt tip.

  • Flying Abilities: Weak fliers

  • Biting Habits: Bite often with a preference for birds over humans

  • Activity Habits: Usually attack at dawn or after dusk

  • Common Species in Southern California: Culex erythrothorax (tule mosquito), Culex quinquefasciatus (southern house mosquito), Culex stigmatosoma (banded foul water mosquito), Culex tarsalis (western encephalitis mosquito)

Culex mosquito
Culiseta mosquito

Culiseta GENUS

  • Breeding Habits: Female mosquitoes tend to lay their eggs in natural, stagnant waters.

  • Physical Attributes: Maxillary palps are longer than the proboscis. Abdomen has a blunt tip.

  • Biting Habits: Prefer to bite livestock rather than people

  • Activity Habits: Prefer cold weather. Active in twilight or dawn.

  • Common Species in Southern California: Culesita incidens (Cold Weather Mosquito), Culesita inornata (Large Winter Mosquito)

Having Problems?

HAVING MOSQUITO PROBLEMS?

WHAT ATTRACTS MOSQUITOES?

  • Carbon dioxide from the breath of humans and animals

  • Body odors such as sweat and lactic acid, combined with heat

  • Dark colored clothing

  • Standing water - females will lay eggs in stagnant water

WHAT TREATS MOSQUITO BITES?

  • Do not scratch bitten area

  • Clean the bite area with plain water, rubbing alcohol, or alcohol wipes

  • Apply an ice pack or ice cubes to the bites

  • Apply anti-itch or itch-soothing creams

WHAT PREVENTS MOSQUITO BITES?

  • Get rid of or change standing water in areas where water collects

  • Avoid going out around dusk to dawn

  • Wear protective clothing  (e.g. long sleeves, long pants)  when in areas where mosquito activity is high

  • Use insect repellents on the skin

  • Treat clothing and outdoor gear with repellents

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