VOA健康报道2022--如何减少蚊子

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How to Cut Down on Mosquitoes

From VOA Learning English, this is the Health & Lifestyle report.

Almost everyone who spends time outdoors has experienced mosquitoes. These bloodsucking insects give itchy bites and can spread disease.

Mosquitoes can spread viruses like West Nile, Zika, dengue and malaria¹. A 2021 report from the World Health Organization estimated that in 2020 there were 241 million malaria cases and 627,000 malaria deaths worldwide.

But there are things people can do to cut down on mosquitoes. You can make it harder for them to reproduce. And you can protect yourself.

Jessica Damiano is a gardening expert. She writes about outdoor living for the Associated Press. In a recent story, Damiano said the best control is prevention. In that story, she gave suggestions on how to cut mosquito populations where you live.

It may seem difficult to avoid mosquitoes. Some areas of the world are densely² populated with them. People who live near bodies of water may experience more mosquitoes. But there are several measures you can take to reduce their numbers.

Mosquitoes need less than a centimeter of water to lay eggs. A female can lay hundreds of eggs at a time. So, check your property for standing³ water. Water can easily collect in small containers – a child's toy, a trash can lid, or a cooking pot.

Get rid of standing water, even if the amount seems small. Make holes in the bottoms of containers that can hold unwanted water.

Other sources of water such as in ponds and bird baths can be treated with chemicals.

Damiano suggests a bacterium⁴ called Bacillus thuringiensis israelensis or Bti for short. The bacterium is a safe and effective way to kill mosquito larvae⁵. Several kinds of Bti are available. Each target different insects. So be sure to buy the one to target mosquitoes.

Bti also comes in several forms, including ring-shaped products called "Mosquito Dunks." These rings float in water and offer 30 days of protection. Experts at the U.S. Centers for Disease Control and Prevention say mosquito dunks "...will not harm people, pets and other animals," and other insects, including honeybees.

You also can make your own mosquito trap. Put a handful of straw, hay, or grass cuttings into a dark-colored container filled with water. Let it sit for one to two days. Then add one mosquito dunk.

If you have many mosquitoes, place several containers around the area. Decomposing⁶ organic matter will attract the insects. They will lay eggs on the treated water. Every 30 days, change the water and add new chemicals to stop future generations of mosquitoes.

Mosquitoes also like overgrown plants. Keep your yard organized. Do not let plants grow too tall.

Running a fan at high speed will reduce mosquito activity. It works by simply blowing the insects away. Also, every time we breathe out, carbon dioxide from our breath attracts mosquitos. A fan can help get rid of our carbon dioxide quickly.

Damiano suggests avoiding chemical poison sprays. These can threaten helpful insects. These chemicals, she warns, only control a small part of the adult mosquito population. Also, she said, insect poisons need to be used several times in a season to work effectively.

Damiano says that so-called "mosquito plants" sold as mosquito repellents contain oils or chemicals that repel⁷ mosquitoes. But the plants do not keep mosquitoes away unless those chemical compounds are released, usually by crushing the leaves. Just having such a plant around will not help.

Some studies claim that citronella and lemongrass oil may provide some protection. But Damiano thinks this has not yet been proven. They may simply hide human scent⁸.

There are other things you can do to protect yourself. Put screens in your doors and windows or keep them closed. Wear long clothing. And cut down on time spent outdoors between the early evening and the early morning. Mosquitoes are most active during that time.

Are mosquitoes all bad?

On the hunt to kill mosquitoes, you may ask yourself if they serve some purpose. Mosquitoes are pollinators, meaning they help some plants reproduce. And they are food for some animals, especially birds and bats. Also, some fish and turtles eat mosquito larvae. But Damiano says that getting rid of mosquitoes where you live will not harm the environment.

Words in This Story

itchy – adj. a feeling of wanting to scratch or rub skin because of an unpleasant feeling on it

larvae – n. a young wingless form (as a grub or caterpillar) of many insects that hatches from an egg

decompose⁹ –v. the natural process of slowly breaking down into simpler materials

attract –v. to cause something to come to a place

spray – n. liquid that is forced out from a container to cover a small area

repellent – n. a substance used to keep something away

screen – n. a woven material that is held together by wood or metal on the sides which is placed in windows to prevent insects from entering

pollinator – n. an animal, often an insect, that spreads pollen from plant to plant permitting plants to produce seeds

1 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

2 densely   

ad.密集地；浓厚地

参考例句：

• A grove of trees shadowed the house densely. 树丛把这幢房子遮蔽得很密实。
• We passed through miles of densely wooded country. 我们穿过好几英里茂密的林地。

3 standing   

n.持续，地位；adj.永久的，不动的，直立的，不流动的

参考例句：

• After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
• They're standing out against any change in the law.他们坚决反对对法律做任何修改。

4 bacterium   

n.(pl.)bacteria 细菌

参考例句：

• The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
• A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。

5 larvae   

n.幼虫

参考例句：

• Larvae are parasitic on sheep.幼虫寄生在绵羊的身上。
• The larvae prey upon small aphids.这种幼虫以小蚜虫为食。

6 decomposing   

腐烂( decompose的现在分词 )； （使）分解； 分解（某物质、光线等）

参考例句：

• The air was filled with the overpowering stench of decomposing vegetation. 空气中充满了令人难以忍受的腐烂植物的恶臭。
• Heat was obtained from decomposing manures and hot air flues. 靠肥料分解和烟道为植物提供热量。

7 repel   

v.击退，抵制，拒绝，排斥

参考例句：

• A country must have the will to repel any invader.一个国家得有决心击退任何入侵者。
• Particles with similar electric charges repel each other.电荷同性的分子互相排斥。

8 scent   

n.气味，香味，香水，线索，嗅觉；v.嗅，发觉

参考例句：

• The air was filled with the scent of lilac.空气中弥漫着丁香花的芬芳。
• The flowers give off a heady scent at night.这些花晚上散发出醉人的芳香。

9 decompose   

vi.分解；vt.（使）腐败，（使）腐烂

参考例句：

• The eggs began to decompose after a day in the sun.鸡蛋在太阳下放了一天后开始变坏。
• Most animals decompose very quickly after death.大多数动物死后很快腐烂。