a type of very small animal with six legs, a body divided into three parts and usually two pairs of wings, or, more generally, any similar very small animal

Ants, beetles, butterflies, and flies are all insects. 蚂蚁、甲虫、蝴蝶和苍蝇都是昆虫。

I've got some sort of insect bite on my leg. 我腿上被小虫咬了一口。