Insects with three-letter names are few, but they include some of the most familiar and important species to humans. Common examples are ant, bee, and fly. Despite their short names, these insects represent highly diverse and widespread groups, each containing thousands of species adapted to different environments across the globe. Unlike frogs, trees, or flowers where dozens or hundreds of distinct species carry distinct common names, the pool of insects whose standard common name consists of exactly three letters is very small indeed.The genuinely established three-letter insect names in English are:
Bee
The most familiar three-letter insect in the world, Bee is the common name applied to thousands of species in the superfamily Apoidea — from the social Honey Bee to hundreds of solitary species. Its three-letter name is among the oldest words in the English language, traceable to Old English bēo and present in virtually every Germanic language in similar form.
Ant
The three-letter name Ant covers over twenty thousand described species in the family Formicidae — the most ecologically dominant group of insects on Earth, comprising an estimated twenty percent of all terrestrial animal biomass. Like Bee, the word Ant is ancient, derived from Old English æmette.
Fly
Fly is both a three-letter insect name and the suffix of hundreds of compound insect names — horsefly, mayfly, firefly — but as a standalone three-letter name it refers specifically to the true flies of the order Diptera, distinguished from all other winged insects by having only one pair of functional wings.
Bug
Bug is a genuine three-letter insect name — technically applying specifically to members of the order Hemiptera, the true bugs, though colloquially used for insects generally. Its etymology is uncertain and somewhat mysterious, appearing in English only from the seventeenth century onward.
Bot
The Bot — as in the botfly larvae of the family Oestridae — is a three-letter name for the parasitic larval stage of flies that develop inside the bodies of mammals including horses, cattle, deer, and occasionally humans. The word bot specifically refers to the larva rather than the adult fly.
Nit
The Nit is the three-letter name for the egg of a louse — specifically the egg of the human head louse Pediculus humanus capitis — cemented to a hair shaft and extraordinarily difficult to remove. While technically referring to an egg stage rather than a free-living insect, it has been an established part of the English entomological vocabulary for centuries.
Beyond these six, genuinely established three-letter common names for insects in standard English usage essentially do not exist. Some languages have more — Japanese entomological common names, for instance, include many short forms — but in English the vocabulary of insect naming overwhelmingly runs to longer compound words.