Katydid

“Katy-did”

Eastern North American true katydids (Pterophylla camellifolia) make a distinctive nighttime call that English ears interpret as “katy-did, katy-didn’t” — three or four raspy notes, repeated at roughly second-long intervals, given from tree canopies on warm summer nights.

The folk name comes directly from this call. The bird-like rhythm and clarity make katydid choruses one of the recognizable summer evening sounds in the eastern U.S.

A wing-rubbing instrument

Like crickets, katydids produce sound by stridulation — rubbing roughened forewings against each other. One forewing has a comb-like row of teeth (the file); the other has a sharp scraper. Drawing the scraper across the file produces the rasping note; rapid repetition produces the song.

The wing structure means only males call — females are silent. Males call to attract mates, advertise territories, and (in some species) negotiate spacing between rivals.

Leaf mimicry — extreme

Many katydid species are masters of leaf mimicry. Their wings can replicate:

• Leaf shape — pointed tips, rounded bases, irregular edges.
• Leaf veins — parallel patterns matching specific host plants.
• Leaf damage — fake holes, fake fungal spots, fake decay edges.
• Leaf coloration — gradients from green to brown matching seasonal changes.

Some tropical species (the Costa Rican leaf katydid, Mimetica spp.) are nearly impossible to spot until they move. The mimicry is so refined that researchers regularly mistake them for actual leaves in field collections.

Predatory katydids

Most katydids are herbivores, but some species are active predators — taking other insects, small lizards, even nestling birds. The shield-back katydids of western North America are notoriously aggressive; the Mormon cricket (technically a katydid, not a true cricket) forms massive migratory bands that strip crops and consume each other in dense swarms.

Diversity centers

The 8,000+ katydid species are concentrated in tropical and subtropical regions, with extreme diversity in:

• Amazon Basin
• Southeast Asian rainforests
• Australian wet tropics
• Central African forests

Many species are still undescribed; new katydids are routinely discovered in tropical surveys.