I couldn’t believe my eyes. There, right in front of me, was a small piece of wood eating a green leaf. I looked again. It was still snacking on the leaf. Was I seeing things(发生幻觉)? Had the hot, tropical sun affected me? After all, it was summer in Costa Rica, a country in Central America.
    I paused, wiping sweat from my eyes. Then I poked（拨弄） the wood with my finger. It stopped. It looked up at me with big, triangular eyes. Surprise! It was a mantid, a kind of insect, instead of a piece of wood.
    The mantid was hanging upside down on a branch. Its wings made it look like a piece of tree bark （树皮）. Then I noticed something else. The leaf wasn’t a leaf at all. The hungry mantid （螳螂）was really eating another insect — a katydid. （纺织娘）By now, all that was left of the katydid was a pair of wings. A few moments later, the wings dropped to the ground. The mantid folded its long legs. It sat still. Now it looked even more like a piece of wood than when I had first seen it.
    I thought about how I had been fooled by these crafty insects. Then I thought about how the two insects go about trying to trick each other. Both mantids and katydids are masters of disguise (伪装). Katydids are particularly good at it. Many look like something they are not. Katydids often look like plants. Many seem to be leaves. Others look like blades of grass. All day, the bugs try to stay perfectly still. Because their bodies look like plants, most predators (食虫动物) don’t bother them while Katydids eat plants.