VOA新闻杂志2025--Monarch Butterfly Count Nears 30-Year Low

An American nonprofit group says the number of monarch¹ butterflies spending the winter in the western United States has dropped to its second-lowest mark in nearly 30 years.

The Xerces Society for Invertebrate² Conservation, based in Oregon, said the causes for this include the use of chemicals to kill insects, known as pesticides⁴. The group also blames reductions in habitat and climate change.

The survey began in 1997

Monarch butterflies are known for their clear orange-and-black markings. They live across North America. Monarchs⁵ in the eastern United States spend the winter in Mexico. The World Wildlife Fund, a non-profit based in Switzerland, counts them there but has not yet released data for this year. Monarchs west of the Rocky Mountains usually spend the winter along the California coast.

The Xerces Society for Invertebrate Conservation has been counting western overwinter populations in California and Arizona for the last 28 years. The highest number recorded was 1.2 million in 1997. The organization announced Friday that it counted just 9,119 monarchs in 2024, a decrease of 96 percent from 233,394 in 2023. The total was the second lowest since the survey began in 1997. The record-low count was 1,901 monarchs in 2020.

The survey noted⁶ that a place in Santa Barbara that saw 33,200 monarchs last winter had only 198 butterflies this year.

Heat might have hurt western monarchs

Monarchs across North America face increasing threats. One is the supply of a plant, milkweed, which they feed on as caterpillars⁸. Monarch Joint⁹ Venture is a nonprofit group based in Minnesota that aims to protect monarchs. The group said milkweed has been disappearing because of dry weather, wildfires, agriculture and urban development. The Xerces Society said pesticides might be on the remaining plants.

Emma Pelton is a biologist with the Xerces Society. She said it is unclear what caused such a sharp decrease in the western population in just one year. The monarch population is already small, she said, and heat above 37.7 degrees Celsius¹⁰ in the western states last year might have slowed breeding.

Monarchs suffer when the temperature gets up to 37.7 degrees Celsius and any temperatures above 42.2 degrees Celsius will kill the insects, Pelton said.

The western states saw a heat wave in July with temperatures in some areas well past 37.7 degrees. Palm Springs, for example, reportedly reached a record 51.1 degrees Celsius on July 5. Another heat wave hit northern California in early October, with several cities breaking heat records.

Western monarchs' future unclear

Pelton said that it is too early to tell what long-term effect the sharp drop might have on the overall western monarch population. Insects can reproduce very quickly, Pelton said. After a low point of 1,901 butterflies in 2020, the population recovered to 247,246 insects the following year, an increase of nearly 13,000 percent. The year after that the survey recorded 335,479 monarchs.

"This is bad news," Pelton said of the 2024 population drop. "But we have seen incredible recovery. This doesn't mean we're not going to have western monarchs."

Federal officials working on protections

The U.S. Fish and Wildlife Service announced in December 2024 that it wanted to list monarchs as threatened. Such a move would ban people from killing¹¹ or transporting them. The proposed change would also ban property owners from making changes to their property that would make it unusable to the butterflies. For example, removing all milkweed from a property would by banned by law.

Earthjustice is an environmental nonprofit legal group based in San Francisco. It asked the Environmental Protection Agency in December 2024 to require testing of pesticides' effects on insects such as bees, moths¹² and butterflies.

I'm Jill Robbins.

Todd Richmond reported this story for the Associated Press. Jill Robbins adapted it for Learning English.

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Words in This Story

pesticide³ - n. a chemical that is used to kill animals or insects that damage plants or crops

habitat -n. the place or environment where a living thing lives

survey -n. a study of a subject aimed at finding something out

caterpillar⁷ -n. an early stage in the life of certain insects

breed - v. to produce young animals, birds, or the like

1 monarch   

n.帝王，君主，最高统治者

参考例句：

• The monarch's role is purely ceremonial.君主纯粹是个礼仪职位。
• I think myself happier now than the greatest monarch upon earth.我觉得这个时候比世界上什么帝王都快乐。

2 invertebrate   

n.无脊椎动物

参考例句：

• Half of all invertebrate species live in tropical rain forests.一半的无脊椎动物物种生活在热带雨林中。
• Worms are an example of invertebrate animals.蠕虫是无脊椎动物的一个例子。

3 pesticide   

n.杀虫剂，农药

参考例句：

• The pesticide was spread over the vegetable plot.菜田里撒上了农药。
• This pesticide is diluted with water and applied directly to the fields.这种杀虫剂用水稀释后直接施用在田里。

4 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

5 monarchs   

君主，帝王( monarch的名词复数 )

参考例句：

• Monarchs ruled England for centuries. 世袭君主统治英格兰有许多世纪。
• Serving six monarchs of his native Great Britain, he has served all men's freedom and dignity. 他在大不列颠本国为六位君王服务，也为全人类的自由和尊严服务。 来自演讲部分

6 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

7 caterpillar   

n.毛虫，蝴蝶的幼虫

参考例句：

• A butterfly is produced by metamorphosis from a caterpillar.蝴蝶是由毛虫脱胎变成的。
• A caterpillar must pass through the cocoon stage to become a butterfly.毛毛虫必须经过茧的阶段才能变成蝴蝶。

8 caterpillars   

n.毛虫( caterpillar的名词复数 )；履带

参考例句：

• Caterpillars eat the young leaves of this plant. 毛毛虫吃这种植物的嫩叶。
• Caterpillars change into butterflies or moths. 毛虫能变成蝴蝶或蛾子。 来自辞典例句

9 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

10 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

11 killing   

n.巨额利润；突然赚大钱，发大财

参考例句：

• Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
• Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。

12 moths   

n.蛾( moth的名词复数 )

参考例句：

• The moths have eaten holes in my wool coat. 蛀虫将我的羊毛衫蛀蚀了几个小洞。 来自《简明英汉词典》
• The moths tapped and blurred at the window screen. 飞蛾在窗帘上跳来跳去，弄上了许多污点。 来自《现代英汉综合大词典》