In the last 25 years, the number of monarch butterflies(帝王蝶) has gone down by hundreds of millions, according to the US Fish and Wildlife Service report. The black and orange butterflies face insecticides(杀虫剂), the habitat loss and the loss of milkweed(马利草)—the plant that monarchs lay eggs on and the caterpillars only eat.
City people making a difference
The smaller number made Field Museum researchers in Chicago ask:What makes a successful monarch garden? Hasle, an ecologist(生态学家)at the Field Museum, and Karen Klinger, a geographer, are working to answer that question.
Many stops along the monarchs' migratory(迁徙的) route are taking an all hands on deck(全员参与的) way to help out the butterfly, looking for more places for milkweed to grow. "We think, in one way, cities are
providing an important place for a lot of insects, "Hasle said. Although the project is still fairly new, there are already some findings.
According to the weekly reports participants sent, more successful gardens had more milkweed and blooming(盛开的) plants or much larger fields. But Klinger said one participant with a single plant watched eggs change all the way to chrysalises(蛹). So, she said, "You just need one plant. "
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In 2020, during the second season of the study, the number of caterpillars dropped, even though the number of participants more than doubled.
Chicago saw a hot, dry summer in 2020, which may have affected(影响) the health of the milkweed plants. In 2021, there was illegal logging (非法砍伐) in Mexico. Spring and summer weather conditions were hard for milkweed blossoms and egg development in the Southern US. All these affected the reproduction(繁殖) of the milkweed plants.
Not giving up
"Now is the perfect time to start planning to plant some milkweed, "Hasle and Klinger said.
"The best thing to do is what you can do, "Hasle said. "One milkweed plant in a pot on your window board is doing something. Maybe it gives you something to look forward to during the boring winter in Chicago. "
