Somewhere out there—likely very near you—mosquito eggs are waiting to hatch.
While some people consider mosquitoes to be little more than a minor, itchy annoyance, these pesky insects can put you at risk for a number of mosquito-borne diseases.
One of the most common diseases transmitted by mosquitoes to humans in North America is West Nile Virus (WNV), which can cause flulike symptoms and, in rare cases, inflammation of the brain (encephalitis). The illness has been reported in every state in the continental US except Maine.
The most recent mosquito-borne disease to cause alarm in the US is Zika virus. If a pregnant woman is infected with Zika virus, her child may be born with a serious birth defect called microcephaly, which is associated with incomplete brain development. People who are bitten by a Zika-infected mosquito can transmit the virus to their sexual partners for months afterward…the virus can also be transmitted when an infected person is bitten by an Aedes aegypti mosquito and that insect successfully incubates the virus before biting another person.
Based on the growing health risks tied to mosquito bites, Bottom Line Health spoke with medical entomologist Dr. Jonathan F. Day to get the truth behind some commonly held myths about what makes the little buzzers bite—and what we can do to stop them…
MYTH #1: Mosquitoes bite only at dusk and dawn. Truth: While most common types of mosquitoes feed mainly at dusk and dawn, some species feed during the day while other species feed at night. In fact, the Aedes aegypti mosquito that transmits Zika virus is most active during the day.
MYTH #2: Mosquitoes are attracted to people who have type O blood. Truth: You may have heard that mosquitoes prefer to bite people with type O blood. Not true. Aside from the fact that type O is the most common blood type in the US, mosquitoes do not choose a host based on blood type.
What does attract mosquitoes: Carbon dioxide. People with high metabolic rates produce more carbon dioxide than do people with low metabolisms—those producing high levels of CO2 (as may occur, for example, during vigorous exercise such as running or biking) attract more mosquitoes.
Another mosquito draw is lactic acid, a compound found in sweat. This means that you’ll be more likely to get an armload of bites if you sit outside after a run.
MYTH #3: You don’t need to worry about mosquitoes if you live in a dry climate. Truth: While mosquitoes are not as abundant in dry climates as they are in tropical rain forests, you will find them ready to bite in dry habitats, including the desert Southwest and the High Plains east of the Rocky Mountains.
Research shows that mosquito populations increase with higher spring soil moisture levels—heavy snowpack, snowmelt and spring rain all provide sufficient standing water to allow the development of immature mosquitoes, even in typically “dry” areas.
For up-to-date forecasts on mosquito activity: Go to the website AccuWeather.com. Add your location to the search box, then look for “mosquito” in the drop-down menu under “Personalized Forecasts.”
For mosquito prevention, keep standing water away from your home. And don’t just look for the obvious places like empty flowerpots or kiddie pools. Be sure to check for water that collects in rain gutters and buckets, too. Empty and refresh water in birdbaths and fountains at least once a week to keep mosquitoes from maturing. Small ponds can be treated with Bti Briquets, a sustained-release larvicide that floats on the water’s surface. Vegetation around larger ponds should be controlled, especially cattails and water hyacinth.
MYTH #4: DEET is toxic to humans. Truth: Developed by the US Army in 1946, DEET (short for N,N-diethyl-meta-toluamide) is one of the few products that is effective against mosquitoes and biting flies. It was registered for human use in 1957 and has been found to be safe even for pregnant and nursing women when applied according to label instructions.
Concerns about DEET come primarily from the toxic effects seen when it is ingested, inhaled or used in other ways inconsistent with label instructions. Do not apply DEET products more often than recommended…and do not apply over cuts, wounds or irritated skin. For more information on DEET, consult the EPA website, EPA.gov/insect-repellents/deet.
MYTH #5: Non-DEET repellents don’t work. Truth: Research published by the Centers for Disease Control and Prevention (CDC) demonstrated that products containing oil of lemon eucalyptus, whose active ingredient para-menthane-diol is derived from the eucalyptus tree, can be as effective as low-concentration DEET. But most botanical formulations require frequent reapplication—usually every 10 to 20 minutes.
Another option is Avon Skin-So-Soft. Its current formula contains picaridin (a synthetic compound that resembles the natural compound found in the plants used to produce black pepper) and IR3535 (structurally similar to the naturally occurring amino acid B-alanine). Both ingredients are registered with the EPA as effective and safe.
MYTH #6: Sprays are more effective than creams. Truth: When it comes to efficacy, what really matters is the concentration of the active ingredient—for example, the CDC recommends DEET, oil of lemon eucalyptus and picaridin-based repellents. This means that a 3% DEET spray and a 3% DEET lotion are equally effective. The downside of an aerosol is the risk for inhalation.
But there are ways to apply a DEET spray without inhaling it. For instance, when using an aerosol, spray the product onto the palm of your hand and apply the liquid to areas you want to treat—your arms, neck and forehead.
Note: Sunscreen/repellent combinations are not recommended—the effectiveness is less than if you used two separate products. When both are needed, apply sunscreen first…then bug repellent.
Also: For unknown reasons, mosquitoes are attracted to dark colors, so wear tightly woven, light-colored apparel. And if you must wear sandals, apply a CDC-recommended insect repellent. Some mosquitoes reportedly love the smell of feet!