Online resources & key organizations
The best place to start:
University of California, Statewide Integrated Pest Management Program (UC IPM). www.ipm.ucanr.edu Search: Mosquitoes.
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NOTE: FEDERAL WEBSITES
U.S. Government websites are not included here because, under the current Administration, some websites have been altered to conform with White House policies that differ from enacted laws, others are no longer updated, and some have been taken down entirely.
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California Department of Public Health (CDPH). www.cdph.ca.gov Search: Mosquitoes. Key document: “Best Management Practices for Mosquito Control.”
California Department of Pesticide Regulation. www.cdpr.ca.gov Promotes “sustainable pest management,” which aims to accelerate adoption of IPM.
San Gabriel Valley Mosquito and Vector Control District (SGVMVCD). www.sgvmosquito.org
The local authority directly responsible.
American Mosquito Control Association (AMCA). www.mosquitoes.org
Mosquito and Vector Control Association of California (MVCAC). www.mvcac.org
Xerxes Society for Invertebrate Conservation
Invertebrates are animals without a backbone and include insects and spiders as well as many other kinds such as worms, snails, and lobsters.
crabs and insects like butterflies. Website includes guidance on reducing use of pesticides and protecting beneficial insects. "The vast majority of invertebrates serve vitally important roles in a healthy environment, including controlling pests, pollinating flowering plants, and providing food for other wildlife. Only a very small number of invertebrates are pests. Yet, pesticides designed to control unwanted plants and animals rarely distinguish between beneficial invertebrates and those which cause harm. All too often pesticides cause unintended consequences and disrupt the natural systems that sustain us."
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OTHER PESTS
The UC IPM website -- www.ipm.ucanr.edu -- has detailed advice on controlling many kinds of pests found locally, including ants, fleas, and venomous spiders (as well as mammals such as mice, rats, opossums, raccoons, gophers, coyotes -- and others).
BITING MIDGES (no-see-ums)
These tiny flies found in MSAG cause painful bites that can itch for days. Methods for abatement are generally the same as for mosquitoes. Small-mesh window screens offer better protection than standard screens, but can reduce air flow.
What's the threat?
>> Top of page: The invasive Asian tiger mosquito (Aedes albopictus)
>> Above: The native southern house mosquito, Culex quinquefasciatus (male/female)
The kinds of mosquitoes that live in MSAG can carry viruses and bacteria that cause serious illness. In a warming climate, insect-borne diseases once found only in the tropics are expanding northward.
WEST NILE VIRUS
This is the most common and most serious vector-borne disease in California and locally. More than 8,000 human cases and nearly 400 deaths have been reported in California since 2003. West Nile is spread by medium-sized, brown Culex mosquitoes (illustration above).
AEDES VIRUSES
Two species of invasive Aedes mosquitoes arrived in Claremont and Pomona in 2016-2017: Aedes aegypti, the yellow fever mosquito, and Aedes albopictus, the Asian tiger mosquito. Both are small, black mosquitoes with white stripes on their back and legs. The large image at the top of the page is of the tiger mosquito; the yellow fever mosquito is very similar. These insects bite during the day and can transmit some of the most debilitating and deadly mosquito-borne viral pathogens known to humans, such as Zika, dengue, chikungunya, and yellow fever. In California, only dengue fever has been found so far.
PROTECTING PETS, NON-TARGET WILDLIFE, AND NATURAL ENEMIES
Insecticides must be applied in ways that minimize harm to our pets as well as vulnerable and beneficial wildlife such as hummingbirds, butterflies, ladybugs, honey bees, and dragonflies. According to UC IPM,
"Most gardens contain far more beneficial insects, than pest insects. . . It is important to encourage these natural enemies by avoiding pesticides that kill them."
RISK OF MOSQUITO BITES BY MONTH IN CALIFORNIA
Chart from the state Department of Public Health . The risk is highest when the weather is hot and mosquitoes are most active. Locally, mosquitoes can still be laying eggs into mid-November.
Moving toward Integrated Pest Management
Moving toward Integrated Pest Management
We don’t need to stop using insecticides suddenly or entirely, but the Gardens should move toward “integrated pest management” (IPM), the effective method called for by California state and local authorities.
The California Department of Pesticide Regulation has a simple definition of IPM: "Any approach that uses the least toxic, effective method to solve pest problems."
Here's a more detailed definition by the University of California’s Statewide IPM program -- www.ipm.ucanr.edu -- which has been a leader globally in developing this method. It defines Integrated Pest Management as “an ecosystem-based strategy that focuses on long-term prevention of pests or their damage . . . Pesticides are used only after monitoring shows they are needed . . . and applied in a manner that minimizes risks to human health, beneficial and nontarget organisms, and the environment.”
USING INSECTICIDES WHEN NEEDED
The state health department cautions that insecticides “must be used by trained personnel and after careful planning.” It calls for applying insecticides selectively to the proper life stage of the mosquito, and in a manner that will “minimize personal hazard to the applicator and other people in the vicinity.”
WHERE MOSQUITOES BREED AND HANG OUT
Mosquitoes go through four life stages: egg, larva, pupa, and adult. Some species lay eggs on stagnant water and usually hatch within a day or two. Others lay eggs on moist soil and don’t hatch until the surfaces are flooded, which may occur months later. Our koi ponds have moving water and were free of mosquito eggs and larvae when tested in 2024; testing will continue. Adult mosquitoes often rest on the back of large leaves of trees and shrubs.
WORKING WITH MSAG’s LANDSCAPE AND INFRASTRUCTURE PROJECTS
Pest control will be taken into account in choosing new plantings and updating irrigation, drainage, wiring, and outdoor lighting systems.
A LITTLE HISTORY
J. Wakeli Wekesa, A Century of Mosquito Control in California, 1915-2015.
MORE FACTS & TIPS
WHAT'S THE LIZARD DOING HERE?
To teach us a lesson.
Mt. San Antonio Gardens is home to a lot of western fence lizards. These little reptiles, harmless to us, are the reason Lyme disease is rare in our region. They are the main hosts for the ticks that carry Lyme disease bacteria, and have a protein in their blood that kills the bacteria in ticks that feed on them.
The lesson is that natural predators like these lizards -- and our owls, hawks, seldom-seen bats, and dragonflies (see below) -- need our understanding and protection.
HERE'S A SCIENTIFIC PAPER BASED ON RESEARCH IN NEARBY ONTARIO
The researchers looked at what goes on in underground stormwater treatment plants in Ontario and Rancho Cucamonga. They focused on Culex quinquefasciatus, a primary vector of West Nile virus in Southern California. Although egg-laying was greatest from mid-July to mid-November, it continued through the winter, pointing to a need to monitor activity all year long.
THE NEXT STEP: SUSTAINABLE PEST MANAGEMENT
Sustainable Pest Management (SPM) was written into California law in 2024. It is defined as a "holistic, whole-system approach applicable in agricultural and other managed ecosystems and urban and rural communities that builds on the existing practice of Integrated Pest Management (IPM) to include the wider context of three sustainability pillars:
- Human Health and Social Equity: mitigate the impacts that pesticides have on communities.
- Environmental Protections: understand linkages between pesticides and broader issues, like water conservation, biodiversity, soil health, and climate.
- Economic Vitality: a broader consideration of economic benefits and impacts."
[Food and Agriculture Code Section 11412] Does this matter to Mt. San Antonio Gardens? Yes, if we are serious about promoting sustainability, including human health. We need to keep in touch with new developments in pest management for our own sake in the Gardens and because our residents are able to spread the word through their own networks. Inserting these few phrases into state law represents a major shift in policy. According to the state Department of Pesticide Regulation, "As climate change and severe weather introduce new and increasing pest pressures, current tools become less effective at managing pests, and scientific studies identify significant impacts of high-risk pesticides that require increased restrictions on their use, California is focused on bringing safe, effective pest management tools to market faster." The goal of the Sustainable Pest Management Roadmap, produced through a two-year collaborative process, is for California, by the year 2050, "to replace priority high-risk pesticide use with sustainable pest management and for sustainable pest management to become the state’s de facto pest management system." For more information, visit the website of the Department of Pesticide Regulation:https://www.cdpr.ca.gov/spm-ipm-overview
HOW TO KEEP FROM BEING BITTEN BY MOSQUITOES
USE A SAFE AND EFFECTIVE MOSQUITO REPELLENT ON YOUR SKIN AND CLOTHING
Go to Consumer Reports -- www.consumerreports.org -- for detailed, up-to-date advice.
Although state and federal agencies have guidance on their websites, their advice is based on recommendations of the U.S. Environmental Protection Agency and may be outdated (see Note on Federal Websites, above).
WEAR THE RIGHT CLOTHING
Consider wearing long sleeves and long trousers that cover your ankles. Avoid wearing dark colors like black, red, and orange. Mosquitoes stay away from white and pale shades of colors.
WHAT ABOUT TAKING VITAMINS ?
Some Gardens residents swear by taking vitamin B to keep mosquitoes from biting them. However, a recent survey of the scientific literature states, "The scientific consensus is, unequivocally, that oral repellents don’t exist. Despite extensive searches, no food, supplement, medication, or condition has ever been proven to make people repellent." What can we conclude? It may be that taking a particular form of vitamin B works for some people against some kinds of mosquitoes.
ARE "BUG ZAPPERS" EFFECTIVE IN CONTROLLING MOSQUITOES?
These electric insect traps may seem to be effective, but mosquitoes aren't attracted to light, and the zaps we hear are when other kinds of insects hit the screen. These include beneficial insects.
DON'T EXPECT PLANTS TO REPEL MOSQUITOES
Some plants like marigolds and mints have compounds that keep insects from feeding on them, but it's not worth planting them because they don’t release them into the air.
HOW ABOUT . . . ?
Consumer Reports tested three methods for controlling mosquito activity in a large outdoor area: citronella candles, an oscillating pedestal fan, and a battery-powered area diffuser that emitted geraniol, a natural repellent derived from plants.
CR found that "the fan is far more effective than citronella candles or the geraniol diffuser. . . . While a fan makes it more difficult for mosquitoes to fly against the steady breeze, it also helps disperse the carbon dioxide we emit when we breathe -- a good thing because mosquitoes use carbon dioxide as a guide to finding humans when they’re looking to feed." www.consumerreports.org
Mosquito repellent coils, which burn over many hours, were not included in this CR project, but are given mixed reviews elsewhere.
Patches, stickers, and wristbands containing mosquito repellents are effective only where they meet the skin.
Introduction of the mos-
quito fish (Gambusia spp.) is likewise
not recommended to control mosqui-
toes; this fish is non-native throughout
much of North America, is a voracious
generalist predator that eats a wide
array of aquatic invertebrates as well
as tadpoles and developing salaman-
ders, and has such a rapid reproduc-
tive rate that it can quickly take over
a small space. In some cases Gambu-
sia introduction can actually worsen a
mosquito problem, as they eliminate
the predatory bugs, beetles, and crus-
taceans that would otherwise prey on
mosquito larvae.
If mosquitoes become an issue,
the pond can be treated with “dunks”
or briquettes of a biological control
agent called Bacillus thuringiensis is-
raelensis, or Bti. This bacterium pro-
duces a crystalline protein toxin that
disrupts the guts of mosquito larvae
that eat it, killing them before they can
develop into adults. Bti is only toxic to
members of the order Diptera (true
flies), so be aware that other groups such as beneficial non-biting midges and crane flies can
also be affected. Mosquito and midge larvae are an important food source for many pond-
dwelling animals, so consider very carefully whether, when, and how frequently treatment
is needed.
DRAGONFLIES
DRAGONFLIES
DRAGONFLIES
Spraying pesticide can harm dragonflies, which are a good example of natural pest control. One dragonfly can eat hundreds of mosquito larvae and adult insects in a day. In the Gardens, they hang out around the koi ponds and fountains.
In Southern California, we have 77 species of dragonflies. This one, the flame skimmer (Libellula sa
Spraying pesticide can harm dragonflies, which are a good example of natural pest control. One dragonfly can eat hundreds of mosquito larvae and adult insects in a day. In the Gardens, they hang out around the koi ponds and fountains.
In Southern California, we have 77 species of dragonflies. This one, the flame skimmer (Libellula saturata) is one of the most common.
Learn more: https://xerces.org/publications/guidelines/backyard-ponds
MONARCHS
DRAGONFLIES
DRAGONFLIES
Spraying pesticide can harm monarch butterflies.
Adult monarchs lay their eggs only on milkweed plants, and monarch caterpillars feed only on milkweed. However, monarchs need milkweed species native to where they live, rather than the tropical species sold in some commercial nurseries. In the Gardens, residents have planted native sp
Spraying pesticide can harm monarch butterflies.
Adult monarchs lay their eggs only on milkweed plants, and monarch caterpillars feed only on milkweed. However, monarchs need milkweed species native to where they live, rather than the tropical species sold in some commercial nurseries. In the Gardens, residents have planted native species and worked with the Administration to remove any tropical milkweed remaining on the grounds. Probably for these reasons, monarchs are frequently seen in the Gardens.
More: T
he main organization focused on insect conservation in North America, the Xerxes Society, has issued a report on the extent of this problem in California and what to do about it to protect these fascinating migratory insects.