Orthoptera
Thirdly, their antennae is different. Katydids and crickets usually have long, thin antennae, while grasshoppers usually have short, thick ones. Of course, this rule does is not perfect – for instance, even though grasshoppers usually have short, thick antennae, the long-horned grasshopper has long, thin antennae like a cricket. Because of this, it is still sometimes hard to tell the members of this order apart.