Before it meant any small creature that creeps, 虫 was drawn as one single animal: a snake, with a triangular head and a body that coils and winds down the bone. Later scribes needed a more specific word for snake and built 蛇 by adding a sound-clue beside this same coiling shape, while 虫 itself relaxed into the general word for small crawling and flying creatures — worms, beetles, ants and all their creeping kin.
A piece of culture
Fighting crickets For centuries, Chinese emperors, scholars and commoners alike have kept crickets purely to watch them fight. The pastime, 斗蟋蟀, was already a passion by the Song dynasty — the chancellor Jia Sidao was so obsessed that he wrote a manual on cricket-keeping and earned the nickname the "Cricket Chancellor," accused of neglecting the empire's business for his insect collection. Prize-winning fighting crickets are still bought and sold for large sums at autumn markets today, kept in tiny clay pots and coaxed into battle with a fine hair.
Use it in a real word
虫子
chóngzi · cung4 zi2
bug; insect — a colloquial word; you already know 子 from "child"