A katydid is a large green insect that looks remarkably like a leaf, with long antennae and powerful back legs for jumping. These insects are masters of camouflage: their leaf-shaped wings have veins that look exactly like the veins in real leaves, making them nearly invisible when they sit still on trees and bushes.

Katydids get their unusual name from the sound males make on summer nights. They rub their wings together to create a loud, rhythmic chirping that sounds like “Katy-did, Katy-didn't.” Some people claim they can hear these insects arguing back and forth: “Katy DID!” “Katy DIDN'T!” The males make this racket to attract females, and on a warm evening, hundreds of katydids might fill the air with their calls.

These insects are related to grasshoppers and crickets but tend to be larger and greener. Most katydids eat leaves, though some species hunt other insects. They're harmless to humans and actually quite fascinating to observe up close, though their excellent camouflage means you usually hear them long before you see them.