Mosquitoes – How To Beat Them Without Joining Them

By : Dr. Roy M. Arnold

Swarms of mosquitoes are an inevitable part of summer, just like the heat, right? Not necessarily. Let’s look at how your outdoor activities can be more enjoyable without worrying about these pesky biting pests.

Most mosquitoes in the US belong to the genus Culex and are flying insects. They are part of a larger order called Diptera that includes gnats and houseflies. The females are the only mosquitoes that bite animals and when they do they suck out tiny amounts of blood. The bite can become inflamed and itchy. Moreover, the bites can, in some instances transmit diseases such as malaria, dengue fever, West Nile virus and Equine encephalitis. Furthermore, mosquitoes can transmit canine heartworm infections to dogs.

Some people are seldom bothered by mosquito bites, while others sitting nearby may be severely bitten. Research has shown that approximately 20% of the population appears delicious to these tiny bloodsuckers. Carefully controlled studies have shown that individuals with type O blood group are the preferred targets of mosquitoes, receiving bites twice as often as those with other blood types. About 85% of people secrete chemicals in their sweat that indicate their blood type. Persons who exhale larger amounts of carbon dioxide also attract more mosquitoes. These people usually are larger or may be pregnant. At least one study has shown that black, dark blue or red clothing attracts more mosquitoes than does white or khaki.

Genetics may also determine the composition of certain chemicals such as uric acid, lactic acid or other substances in sweat. These chemicals attract mosquitoes. Unfortunately, people can’t change their genetics.

Mosquito control has to be multi-directional – aimed at reducing the breeding habitat for mosquito larvae and by controlling the adult population. Mosquitoes lay their eggs in water and their young develop in water. Any source of standing water can serve as mosquito breeding ground so it is important to reduce the presence of standing water in and around your home by landscaping, removing old tires or open containers where water can collect. If you have ornamental ponds or fountains, stocking them with fish that feed on mosquito larvae is a good idea. Swimming pools that are properly chlorinated and balanced generally don’t support mosquito breeding.

Spraying with insecticides can help control adult mosquitoes as can introducing predatory species such as dragonflies. Dragonflies prey on mosquito larvae and on adult mosquitoes. While bats and insect-eating birds like to snack on mosquitoes, they really don’t reduce the population noticeably.

Certain plants such as geraniums, marigolds, lavender, mint or basil can repel mosquitoes. These plants should be placed around the perimeter of the yard or in planters or window boxes close to where humans will gather. Mechanical traps can be very effective. These traps emit heat and chemicals like carbon dioxide or lactic acid that mimic humans and attract scores of mosquitoes. So-called “bug zappers” don’t attract biting insects at all so they are probably not worth the investment if mosquito control is your goal.

Screens or netting are also very effective. A low-tech solution to the mosquito problem is to use an oscillating fan near your outdoor recreation area. Mosquitoes are fairly weak flyers and generally can’t tolerate the mild breezes generated by fans. Water misting systems can serve a dual purpose by keeping the outdoor area cool and mosquito free. Finally, tiki torches or candles made from citronella oil are very effective in repelling mosquitoes. If these aren’t practical, topical insect repellants containing citronella or other chemicals can be very effective.

The redness, itching and swelling that accompanies mosquito bites is a result of enzymes in the mosquito’s saliva injected during the biting process. So what can be done to relieve the itching once you have been bitten? Home remedy recommendations abound. Aloe, vinegar, lemon juice, baking soda and toothpaste have all been recommended. Over the counter medications like calamine lotion or hydrocortisone cream are also effective. Sometimes the itching requires an antihistamine like diphenhydramine (Benadryl) or loratidine (Claritin.)

When should you seek medical attention for mosquito bites? First and foremost, if high fever, headache, stiff neck or decreased level of consciousness develops, seek medical attention immediately. These can be the signs of a mosquito-borne illness like West Nile or Equine encephalitis. If the bites become very large or inflamed, or are accompanied by hives or red streaks medical evaluation is advisable.

By taking a few simple precautions – wearing light-colored clothing, and using screens, mosquito-repelling plants, topical repellants and outdoor fans, misters or traps, you can enjoy the outdoors this summer and largely avoid mosquitoes.

References: Smithsonian Magazine online, July 12, 2013. Mayo Clinic Health online.