The original meaning of "虫" was snake. The ancient character looked like a snake with a pointed head, and a curving body. Later the connotation of "虫" was extended to refer to all insects and worms.
1.一只母鸡和两只小鸡正在吃虫子。 Yì zhī mǔjī hé liǎng zhī xiǎojī zhèngzài chī chóngzi. One hen and two chicks are eating worms.
2.蚊子是害虫。 Wénzi shì hàichóng. Mosquitoes are pests.
3.也许人们认为填写歌词是一种雕虫小技,但是把它写好却不容易。 Yěxǔ rénmen rènwéi tiánxiě gēcí shì yìzhǒng diāo chóng xiǎo jì,dànshì bǎ tā xiě hǎo què bù róngyì. People may consider writing lyrics as a simple task; however, it's really hard to write a good one.