When we talk about pest control in gardens, we think about the insects that want to eat our vegetables and ornamentals, but there is a major pest that wants to feed on gardeners themselves — the mosquito. For a better understanding of mosquitoes and effective mosquito control, my guest this week, Raven Forrest Fruscalzo of the podcast “Tiny Vampires,” is here to share the vetted facts and dispel misconceptions.
Raven is a South Florida native who now lives in the state of Washington, where she is a freelance science communicator for public health agencies, medical science and entomology. She believes a more scientifically literate public creates a healthier society. To that end, she translates scientific information into conversational, story-based podcasts. In “Tiny Vampires,” she explains all about mosquitos and other blood-sucking arthropods in response to listener questions.
Raven holds a Master of Science in biology from the University of Notre Dame in Indiana. It was while she was a Ph.D. candidate at Notre Dame that she began podcasting. The Zika virus was emerging as a public health concern, and she was a mosquito researcher who was interested in science communication. “I was hearing a lot of misinformation and confusion by the public and by the media about vector-borne diseases in general and especially mosquitoes in particular,” she recalls.
There was a lot of fundamental misunderstanding of basic mosquito biology, Raven says, so she sought to better inform the public through the medium of podcasts. Her university helped her launch her podcast, and she decided to leave her Ph.D. program to become a full-time science communicator.
Raven wanted to base the podcast on what the public wants to know. “A lot of science communication is scientists or science writers guessing as to what the public wants to know about,” she says. But when she tells non-scientists that she studies mosquitoes, they ask all sorts of questions she never would have guessed. It’s those unexpected questions that her podcast answers, and she explains how scientists were able to figure out those answers. Each episode also shares how the general public can practically use the information.
Mosquito Bites Affect People Differently
Allergic reactions to mosquito bites vary from person to person. Raven, like me, is mostly unbothered by mosquitoes. Even when she is bitten, she doesn’t get the itchy rash that is associated with mosquito bites. She remembers watching hundreds of Anopheles gambiae — the mosquito that can transmit malaria and almost exclusively feeds on humans — bite her arm in a lab, and they barely left a mark. Meanwhile, Raven’s husband breaks out in hives from one bite.
How Our Microbiomes Make Us a Target for Mosquitoes
Our skin is covered in bacteria — the good, the bad, the ugly, Raven says. Certain bacteria release volatile compounds that attract specific mosquito species. One colony of bacteria can be very attractive to the mosquitoes in Florida while it’s not attractive at all to the mosquitoes in Alaska. So that’s why you couldn’t get bit up in one place and left alone in another, even if both places have large mosquito populations.
The microbiome can also be affected by diet, so what you eat on a particular day may make you more attractive to mosquitoes.
One experiment Raven cites involved asking the participants to wear the same pairs of socks for a week without washing them. Then the volatile compounds were rubbed off the socks and onto glass beads so scientists could test how attracted the mosquitoes would be to high volumes of those compounds. Whether being freshly showered keeps mosquitoes at bay is still an open question.
Mosquitoes & Carbon Dioxide
Another way mosquitoes find people to bite is by detecting the carbon dioxide that we breathe out. However, they must be fairly close by because they aren’t smelling the CO, they are tasting it, Raven points out. The mosquitoes use their gustatory receptors (that are on tongues) instead of olfactory receptors (that are in noses).
There are mosquito traps that use CO as bait, but they will only attract mosquitoes from a short distance.
Raven points out that mosquito traps used by mosquito control departments catch pounds of mosquitoes in a night, but the traps are not for control. Those traps exist to capture mosquitoes to test them for diseases. They don’t even put a dent in the mosquito population.
The Ecological Importance of Mosquitoes
Believe it or not, mosquitoes have some redeeming qualities. Raven doesn’t have any hesitations about eradicating the diseases that mosquitoes transmit, but eliminating mosquitoes themselves is a different question.
Mosquitoes’ primary ecological value is to the food chain. For instance, dragonfly larvae eat mosquito larvae, and then the adult dragonflies go on to control other insect populations. Up the food chain, bats eat dragonflies. Some birds, such as purple martins and hummingbirds, love to eat mosquitoes.
And while mosquitoes are thought to survive off blood, that is not the whole story. It’s only the females that suck blood (so they have the fats and proteins needed to produce eggs), while both males and females feed on nectar as their primary source of energy. As nectar feeders, mosquitoes are pollinators, though we avoid staying outside and being in the garden at dawn and dusk while mosquitoes are most active, so we never get to observe mosquitoes on flowers eating nectar.
The disease-carrying capacity of mosquitoes is also important as they control mice, deer and other populations.
Mosquito-Borne Diseases Affecting Humans
Malaria has been eradicated from the United States but kills millions of people globally each year. Yellow fever likewise is not found in the United States but is responsible for tens of thousands of deaths annually worldwide. And then there’s Dengue fever, which kills hundreds each year.
Yellow fever is a virus preventable by a vaccine, while malaria is a parasite with a vaccine that just became available a few months ago. There is no vaccine for Dengue fever, which is nicknamed “breakbone fever” because it can cause muscles to cramp so much that bones break. Dengue is actually worse upon the second infection, unlike most diseases, which provide some immunity after a first infection is fought off.
In the United States, mosquitoes are controlled over Dengue and Zika concerns, as well as West Nile virus, St. Louis encephalitis and eastern equine encephalitis. None have vaccines available.
Mosquito-Control Districts & Public Health Organizations
Because many mosquito-borne diseases in the United States are transmitted from birds to people via mosquito bites, some mosquito control districts place cages around the district with chickens inside them. By drawing blood from the chickens, they can detect if a mosquito-borne disease is circulating in that area. The chickens act as canaries in a coal mine. Then instead of spraying an entire city all the time, the use of pesticides for mosquito control can be limited to where it is needed.
As a kid in Miami, I would run behind the mosquito fogger truck, disappearing in a cloud of who knows what. I would also climb trees when planes fogged the streets. I’m still standing today, decades later, but we know a lot more now about pesticides and the danger of exposure. Fog applications are also more precise today in terms of how the fog lands and spreads.
Raven says that in Florida in those days, prior to 1972, those trucks were likely spraying DDT. In fact, dousing neighborhoods in DDT is one of the ways that yellow fever and malaria were eradicated from the United States. The planes may have been applying DDT or malathion.
DDT was associated with patriotism in the years after World War II because it was used to keep our troops healthy and our victory gardens pest-free, Raven says. “It was often over and over again touted as being very safe by the manufacturers and by the general media.” But even then the scientists said they only tolerated the threat of the chemical because it was considered less devastating than the threats it conquered. Back then polio was also thought to be spread by flies, so that misconception worked in DDT’s favor as well.
When the threats went away, the public finally took a hard look at DDT and its consequences. Rachel Carson’s “Silent Spring,” published in 1962, called attention to how chemicals were adversely affecting the environment, such as DDT’s negative effect on peregrine falcon populations. And DDT is persistent: It’s still being found in fish in Washington State.
Today’s Public Health Mosquito Sprays
Today, many vector control operations use pyrethroids, which are synthetic versions of the natural pesticide pyrethrum. Pyrethrum is derived from chrysanthemum flowers and feverfew, while pyrethroids are manufactured.
The nozzles on modern mosquito foggers make the droplets of the spray very, very tiny, so they stick to mosquito wings well and not as well to other insects. Applications are also timed to when mosquitoes are most active. So for instance, Culex mosquitoes bite in the evening and the morning, when native bees are less active. However, Aedes aegypti mosquitoes, which are causing issues in California right now, are daytime biters.
Aerial applications are also more precise than they once were. Planes now use just a sugar packet’s worth of pesticide over an acre in closely monitored applications.
Sometimes vector control specialists will use backpack devices to target specific areas. However, the companies that perform these services privately will often spray an entire yard indiscriminately with no regard for when the pollinators are most active. Raven notes that it’s always best to call your local health department and ask for a free service before enlisting a private company.
Mid-day applications are basically a waste of money anyway because the mosquitoes are elsewhere at that time, hiding under leaves in the woods rather than hanging in your yard. Plus, the broad-spectrum pesticides, even the “natural” ones, will kill many non-target, beneficial insects.
Another strategy used today is to rotate the pesticides used so the mosquito populations don’t develop a resistance to any control method.
Biological Controls for Mosquitoes
The aptly named mosquitofish is effective at controlling mosquito larvae. Some public health agencies are distributing these fish to homeowners who are no longer maintaining their pools. When added to stagnant pool water or a pond, the fish make quick work of mosquito larvae.
Some public health organizations also distribute Mosquito Dunks, which contain Bacillus thuringiensis israelensis, or Bti, a type of bacteria that kills mosquito larvae. Mosquito Dunks and Mosquito Bits are available to anyone to add to stagnant water anywhere, and it is safe around pets and humans.
Using Insect Repellent
An insect repellant spray containing DEET will last for eight hours or even longer. If you choose to use a natural repellent product, such as citronella and lemongrass, Raven advises reapplying once every three hours to stay protected from mosquito bites.
I hope you learned something about safe and responsible mosquito control and how to better protect yourself. If you haven’t listened to this episode yet, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.
What unanswered questions do you have about mosquito control? Let us know in the comments below.
Links & Resources
Some product links in this guide are affiliate links. See full disclosure below.
joegardener Online Gardening Academy™: Popular courses on gardening fundamentals; managing pests, diseases & weeds; seed starting and more.
joegardener Online Gardening Academy Master Pests, Diseases & Weeds: Learn the proactive steps to take to manage pests, diseases and weeds for a more successful garden with a lot less frustration. Just $47 for lifetime access!
joegardener Online Gardening Academy Perfect Soil Recipe Master Class: Learn how to create the perfect soil environment for thriving plants.
joegardener Online Gardening Academy Beginning Gardener Fundamentals: Essential principles to know to create a thriving garden.
joegardener Online Gardening Academy Growing Epic Tomatoes: Tomato expert Craig LeHoullier joins me in leading this course on how to grow healthier, productive tomato plants and how to overcome tomato-growing challenges.
Disclosure: Some product links in this guide are affiliate links, which means we get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us, and compensation is not an influencing factor on their inclusion here. The selection of all items featured in this post and podcast were based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Rain Bird, Corona Tools, Milorganite, Soil3, Exmark, Greenhouse Megastore, High Mowing Organic Seeds, Territorial Seed Company, Wild Alaskan Seafood Box and TerraThrive. These companies are either Brand Partners of joegardener.com and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.