The noun 毛虫 (máochóng) means 'caterpillar,' the larval stage of a butterfly or moth. It is composed of 毛 (hair/fur) and 虫 (insect), literally meaning 'hairy bug,' describing the fuzzy appearance of many caterpillar species. It is commonly used in nature and biology contexts.
树叶上有一条绿色的毛虫。
Shùyè shàng yǒu yī tiáo lǜsè de máochóng.
There's a green caterpillar on the leaf.
小孩子看到毛虫吓得大叫。
Xiǎo háizi kàn dào máochóng xià de dà jiào.
The child screamed in fright when seeing the caterpillar.
毛虫长大以后会变成蝴蝶或者蛾子。
Máochóng zhǎng dà yǐhòu huì biàn chéng húdié huòzhě ézi.
When caterpillars grow up, they turn into butterflies or moths.