How flightless beetles wander the Pacific

PACHYRHYNCHUS WEEVILS are found on most islands in the eastern Pacific Ocean. If these weevils could fly, that would not be surprising. But they cannot. Why they are so widespread is therefore a mystery. But it is one that Wen-San Huang of the National Museum of Natural Science in Taiwan thinks he has solved.One theory, which dates back to 1923, is that the beetles drift from place to place, buoyed up by a tiny air cavity each has beneath its outer shell, which allows the insects to float. Dr Huang’s research into the weevils began when he noted that this theory had never been tested. He discovered, when he put it to the test, that the beetles do, indeed, float. But, as he reports in , floating in seawater does not do them much good. All 57 adults he tried it with died within two days. Clearly, adult weevils are not good sailors.