To catch a butterfly in English, you would say "to catch a butterfly." The phrase is derived from the verb "to catch," which means to capture or apprehend something, and the noun "butterfly," which refers to a flying insect with distinctive, colorful wings. Here are some example sentences:

I saw a beautiful butterfly in the garden and I tried to catch it.

The little boy ran after the butterfly, trying to catch it in his net.

My sister loves to catch butterflies and put them in a jar to admire their colors.

In Chinese, the phrase "捉蝴蝶" (zhuō húdié) literally means "to catch a butterfly."