害虫 (hài chóng) literally means 'harm-insect' — 害 (hài) means 'harm' or 'to harm', and 虫 (chóng) means 'insect' or more broadly 'creeping creature'. Though the character 虫 suggests insects, in modern usage 害虫 refers to any organism that causes damage to crops, livestock, stored food, buildings, or human health — including rodents, fungi, nematodes, and even some birds or weeds in agricultural contexts. It’s a functional, neutral-to-negative term widely used in farming, gardening, public health, and environmental management.

The word emphasizes the harmful impact rather than biological classification. Unlike colloquial terms like 小强 (xiǎo qiáng, cockroach) or 蚊子 (wén zi, mosquito), 害虫 carries no affection or humor — it’s technical and evaluative, often appearing in official reports, pesticide labels, and pest-control advice. It’s commonly paired with verbs like 消灭 (xiāo miè, 'to eliminate'), 防治 (fáng zhì, 'to prevent and control'), or 危害 (wēi hài, 'to harm').