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The buzz on mosquitoes: how to protect yourself in skeeter season

In this Sept. 5, 2014 file photo, workers spray insecticide in Yoyogi Park in Shibuya Ward, Tokyo, after a mosquito carrying the dengue fever virus was discovered there. (Mainichi)

Once again, the season of bites, itchiness -- and sometimes even diseases -- is upon us as mosquitos begin their yearly activities. Of course, everyone would like to live mosquito-free, so the Mainichi Shimbun has summarized some of the best ways to deal with the pests.

    It is said that there are roughly 100 different species of mosquitos in Japan alone. Most people are probably familiar with the Asian tiger mosquito, belonging to the genus Aedes with its distinctive stripes, that buzzes in the daytime and can carry infectious diseases such as dengue fever, or perhaps the common house mosquito that comes out in the evening and flies around your room at night, disrupting your sleep.

    "Originally mosquitos in the genus Aedes weren't found in northern Japan," said marketing department member Yuji Nakatsuji of pharmaceutical company Earth Chemical Co., "but due to global warming, their habitat has been expanding gradually northward." Aedes is most active at temperatures between roughly 25 and 30 degrees Celsius, and they slow down significantly on days where the temperature exceeds 35 degrees Celsius and may even die.

    Mosquitos usually rely on food sources such as the nectar of flowers. Only the female mosquito sucks human blood when laying her eggs. Because the eggs need blood from other animals as a source of protein-rich nutrients, the female mosquito is sensitive to smells like that of human sweat and the carbon dioxide contained in human breath. The reason that children are so often bitten by mosquitos is because of their higher body temperature which causes them to sweat more. The same is true of those who are drunk -- body temperature and the rate of respiration increases due to the ingestion of alcohol. People who often engage in outdoor activities like camping and barbeques where alcohol may be consumed have to be extra cautious about mosquitos.

    The first method to battle the pests is working to make sure their numbers don't increase. The most effective countermeasures are to keep mosquitos from laying eggs or clean up larvae, rather than trying to exterminate the adult insects. Mosquito larvae mature in bodies of water, so there are no mosquitos born in areas without standing water. After an outbreak of dengue fever in 2014, the following year the Tokyo Metropolitan Government designated June as the month for stepped-up efforts to prevent the breeding of mosquitos, and also focused on educating Tokyoites about the issue. "It's only the third year of the project, but awareness and concern about mosquitos is rising," said a representative from the Environmental Health and Sanitation Division of the metropolitan government.

    Among the Tokyo government's recommended countermeasures are cleaning up unused open cans and tires and removing objects that can accumulate standing water in residences and surrounding areas. As for saucers under potted plants or vases for flowers which need to be filled with water, people are advised to clean them frequently and change the water at least once a week. It is reportedly possible for eggs of the Asian tiger mosquito to incubate in only 1 cubic centimeter of water. Additionally, the common house mosquito can mature from an egg to an adult in a span of roughly 10 days if conditions like temperature are just right. During mosquito season, the most important thing is to not overlook even the smallest amount of standing water.

    But even then, no matter how much attention is paid to making it more difficult for mosquitos to breed, they can't be completely wiped out. To avoid mosquitos that have already successfully made it to adulthood, there are a variety of options to keep the pests away.

    Citronella, geraniums, lemongrass, and the citronella-geranium hybrid "mosquito plant" and other herbal remedies that are said to keep the insects away with their smell are widely known, however experts are in agreement that just having a single plant does not mean that mosquitos will completely go away, and warn that the plants are not recommended as a realistic "mosquito repellent" method. If you really want to keep mosquitos away, you have no choice but to depend on burning mosquito coils and other methods that use chemicals. Many such products exist for both inside and outside the home.

    When using mosquito repellents on the market that are applied directly to the skin, it is important to follow the rules for the application and amount of the product used. You want to steer clear of insect repellants containing the chemical "DEET." The Ministry of Health, Labor and Welfare cautions that children less than six months old should not use DEET insect repellents, while children over six months old but younger than 2 years old should only use such repellents once a day and children between the ages of 2 and 11 should use repellents once to three times a day, with the product never applied to the face, among other recommendations. When selecting a mosquito repellant for infants, it is crucial to check the label for the contents before purchase.

    For those with allergies that prevent them from using chemical repellents, the best course of action is to wear long sleeved shirts, pants and socks to reduce the amount of exposed skin, and to frequently wipe or wash off sweat. "Mosquitos are attracted to dark clothing, so wearing white reduces your chances of being bitten," advised Nakatsuji.

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