Crickets are medium-sized to large insects. Like their relatives the grasshoppers and katydids, they have chewing mouthparts, and their back legs are larger and stronger than than the other two pair. They have rounded heads, antennae that are long and thin, and their wings bend down on the sides of their body. Unlike katydids, crickets often look flat, or at least the top of their body is flattened. Most crickets are brown, but some are black and some tree crickets are green with whitish wings. Most male crickets chirp by rubbing their front wings together, their wings have special structures for this. Both males and females have ears, but they are on their legs! They are smooth round structures on their lower legs. Female crickets have a thin round tube on the end of their abdomen that they use to lay their eggs. This structure is a called an ovipositor. Female katydids have an ovipositor too, but it is flattened, while the crickets' ovipositor is round.