Crickets are insects related to grasshoppers and katydids (order Orthoptera). They have somewhat flattened bodies and long antennae. Crickets are known for the loud chirping noises they make by rubbing their corrugated wing casings against combs on their hind legs. The females have a long needlelike egg-laying organ (ovipositor). There are about 900 species known worldwide.
Crickets are popular pets in Asia, especially China.
Subfamilies
Family Gryllidae - True crickets
Eneopterinae - Bush crickets
Gryllinae - Common or field crickets; brown or black; despite the name, some of them enter houses.
Mogoplistinae - Scaly crickets
Myrmecophilinae - Ant crickets
Nemobiinae - Ground crickets
Oecanthinae - Tree crickets; usually green with broad, transparent wings; frequent trees and shrubs.
Pentacentrinae - Anomalous crickets
Trigonidiinae - Sword-tail crickets
Family Gryllotalpidae - Mole crickets; thick-bodied brown insects with forelimbs that are highly developed for burrowing.
In addition to these, several other orthopteran species are also called "crickets", although they are not strictly crickets: