【英语时差8,16】会发射紫外线的蜘蛛（上）（在线收听）

Many spiders make their webs attractive to insects by using special silks that reflect ultraviolet light, according to a study by two scientists working at Yale University. Ultraviolet light is the component of sunlight that causes suntans and sunburns. We can’t see ultraviolet light, but insects can. Ultraviolet light seems to provide at least two important signals to insects. First, it signifies open space, because the only natural sources of ultraviolet light are the sun and the sky. Second, ultraviolet-reflecting bars, crosses, circles, and other patterns on flowers serve as targets that attract pollinating insects. The authors of the study, Catherine Craig and Gary Bernard, found that many spiders make webs entirely of silk that reflects ultraviolet light. Apparently these webs attract insects because the webs look like patches of open sky to insect eyes.