Katydids and common grasshoppers are often mistaken for one another, but they are distinct types of insects. While they share a close evolutionary relationship, they have clear biological differences. The confusion arises because both are jumping insects that often share similar green coloration. Examining their specific structural and functional characteristics provides the tools for accurate identification.
Shared Taxonomic Classification
Katydids and grasshoppers both belong to the insect Order Orthoptera, which translates to “straight wings.” This order includes insects characterized by powerful hind legs adapted for jumping and the ability to produce sound through friction, known as stridulation.
The two groups separate at the family level. Katydids belong to the Family Tettigoniidae, informally called “long-horned grasshoppers.” Conversely, most common grasshoppers belong to the Family Acrididae, known as “short-horned grasshoppers.”
Key Physical Identification Differences
The most reliable way to distinguish the two insects is by examining the length of their antennae. Katydids possess extremely long, thin, thread-like antennae that are often equal to or longer than their entire body length. Grasshoppers, in contrast, have significantly shorter, thicker antennae that rarely extend more than half the length of their body.
Another physical difference is the location of their auditory organs, called tympana. Katydids have their tympana situated on the tibiae of their front legs. Grasshoppers have their ears located on the sides of their first abdominal segment.
Female insects can also be differentiated by the ovipositor. The female katydid has a long, visible, and often sword-like ovipositor extending prominently from the abdomen. Female grasshoppers possess a much shorter, blunter ovipositor. Many katydids have wider, more robust bodies that mimic the shape of a leaf, while grasshoppers typically exhibit a more slender profile.
Behavioral and Auditory Distinctions
The timing of activity is a major behavioral difference. Grasshoppers are predominantly diurnal, meaning they are active and communicating during the daytime. Katydids are typically nocturnal or crepuscular, with most singing and movement occurring after dusk.
The method they use to produce sounds, or stridulation, also differs fundamentally. Male katydids create chirps by rubbing the base of their two forewings together, using a scraper on one wing against a file-like ridge on the other. Grasshoppers employ a different mechanical process, rubbing their hind legs against the hardened forewings. They utilize a row of small pegs on the inner surface of the hind femur to scrape against the wing edge.