Western monarch butterflies(WMBs, 西部帝王蝶) fly thousands of miles every year, flying north in spring and summer, and south in fall. Now, scientists want people in the western US to give them a hand by sending in any pictures of monarchs they take this spring.

WMBs, like most butterflies, help plants create seeds, which can then create more plants by spreading a dust called pollen between plants. In turn, monarchs depend on plants. They gather sweet nectar (花蜜) from flowers for food. They rest and spend their winters in trees. And they depend completely on a plant called milkweed to lay their eggs.

Their number has been dropping sharply since the 1980s, when 3 million to 10 million butterflies migrated (迁徙) annually from the northwestern United States to spend the winter at hundreds of sites along the California coast. In 2020, less than 2, 000 monarchs were counted in the entire state. But in 2021, that number jumped to 247, 237. Scientists still don't fully understand this phenomenon. But they're studying it, saying it'll take years of tracking them to work it out.

Scientists have learned a lot about where Western monarchs spend the winters. But they know much less about where they go when they leave their winter homes. That's why scientists from several universities are organizing a project called "Western Monarch Mystery Challenge" to seek for practical assistance from "citizen scientists" in the American west.

They're asking anyone who sees a monarch butterfly outside of their winter homes this spring to take a picture and send it to them. By collecting the pictures, along with the date and place where the pictures were taken, scientists hope to learn more about what happens to the butterflies and where they are after they leave their winter homes and protect them better in the future.

Last year's increase in monarch number is great news. But the number of monarchs is still way below the millions of butterflies that migrated in the 1980s.

My grandmother moved into an old people's home and I visited her there. She was sitting in the living room with other residents, half of them asleep. The room was clean and the care assistants were kind and cheerful. A general knowledge quiz show was on the television and the only other sounds were snoring (打呼噜). Grandma talked a lot about how much she missed her grandson but I hated going to visit her there and, to be honest, I couldn't wait to get away myself. 

So I was interested to read a newspaper article about a new concept in old people's homes in France. The idea is simple, but revolutionary—combining an old people's home with a nursery school in the same building. The children and the residents eat lunch together and share activities such as painting and gardening. In the afternoons, the residents enjoy reading or telling stories to the children, and if a child is feeling sad or tired, there is always a kind lap to sit on. Nowadays there is less and less contact between the old and the young. There are many reasons for this, but the result is the same: increasing numbers of children without grandparents and old people having no contact with children, and more old people who feel lonely and useless, along with more and more families with young children who desperately need more support. It's a major problem in many societies. 

That's why intergenerational programmes, designed to bring the old and the young together, are growing in popularity all over the world. There are examples of successful initiatives. Young people teaching IT skills to older people is one obvious example. Old people working as volunteer assistants in schools is another, perhaps reading with children who need extra attention. 

The advantages are enormous. The children are happy because they get more individual attention. They also see illness and death and learn to accept them. The residents are happy because they feel useful and more interested in life. There will be less conflict in a community if older people can understand the youth, and vice versa. 

Now we need to rediscover what "community" really means. Then perhaps getting old won't be such a depressing prospect after all.

In order to get rid of goldenrod from the city, the government of Wuhan is encouraging residents to report any findings of the plant, which is classified as a harmful alien （外来的） species.

Goldenrod is one of the most successful and widespread alien plant species. It is often referred to as "the flower of the devil", as it spreads extremely fast and causes other plants to die.

Besides Hubei province, the plant has also been found expanding in other provinces such as Jiangxi and Zhejiang. Although local authorities have tried to get rid of the plant, it is proving to be a difficult task. Goldenrod represents just one of the alien species that are aggressive towards the country's native species. Statistics show that by 2020, nearly 800 kinds of alien species had invaded （侵略）the country, among which 638 species have invaded the country's agricultural and forestry ecosystems, causing direct economic losses of about 200 billion yuan ($ 31. 36 billion).

At the United Nations Biodiversity Conference held in Kunming, Yunnan province, the invasion of alien species was the subject of discussions, as it was regarded as one of the two most important factors leading to the loss of biodiversity, the other being human-caused ecological damage.

China passed its Biosecurity Law on April 15, 2021, which provides the legal basis for preventing the invasion of alien species and protecting biodiversity in the country. The relevant departments also strictly carry out port inspections and quarantines （检疫）so as to keep harmful organisms out of the country, and they strengthen early warning and monitoring systems so as to address the invasion as early as possible.

However, while government departments are making every effort to prevent and control the situation, the participation of the people should not be ignored. It is also necessary, as Wuhan is doing, to encourage people to pay attention to invasive species and actively play a role in keeping them at bay. Preventing any invasion by an alien species and protecting biodiversity should not just be the government departments fighting alone, but also a people's war.