Experts say the American state of Hawaii has been invaded (入侵)by a small frog called the coqui (ko--kee). There may be millions of the small frogs in Hawaii. However, they do not belong there. They are normally found in the southeastern United States. The coqui frogs are harming Hawaii’s environment. And the extremely loud noise they make is causing problems for Hawaiian citizens and visitors. The coqui invaders arrived in Hawaii about ten years ago. They were believed to have been brought in accidentally in shipments of plants from Florida. Their number has sharply increased. They have quickly spread around the Hawaii Islands hidden in plants. The coqui is a brown frog about five centimeters long. During the day, the frogs hide in wet protected areas, such as under plant leaves. At night, the frogs move onto trees to feed, call to females and mates. The call of the male coqui sounds like. Ko kee! Ko kee! In the southeastern United States, local people celebrate coqui frogs. But in Hawaii, the foreign frog has been considered as a harmful animal. The coqui frogs are a major danger to Hawaii’s environmental system. The frogs eat thousands of insects (昆虫)every night. These insects are important for the reproduction of plants. The insects also are important food for Hawaii’s native rare birds. The frogs also are affecting the tourism industry in Hawaii. Increasing numbers of hotels, visitors and local people have been annoyed by the loud calls made by male coqui  frogs to female frogs. At night, the noise often makes it difficult for people to sleep.The frogs do not have any natural enemies in Hawaii to reduce their population size. The warm weather permits them to lay eggs all year long. There are many efforts in Hawaii designed to stop the spread of the coqui. It is a crime to transport ,sell or release(释放)the frogs there. The Hawaii Department of Agriculture is trying to find an effective chemical that can be safely used to kill the frogs. For now, the frogs may only be caught by hand. The Hawaii Department of Agriculture says the greatest danger to the economy and environment of the state is from harmful species, like the coqui. 小题1:The statement that can best summarize the main idea of the passage is .
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