About
虼 is a phono-semantic compound: the semantic insect radical 虫 places it within the category of bugs and creeping animals, while 乞 provides its phonetic element. This character has a narrow function, appearing almost exclusively in the compound word 虼蚤, a regional term for "flea". It was created solely to represent this specific jumping insect in writing, with no extended metaphorical or abstract uses. Its history is straightforwardly taxonomic, serving only as the written form for a particular pest.