Don’t mix this up with kupu-kupu malam (prostitute)
Sould it not be plural?
Dear Bratsche, plural is also possible, butterfly = "kupu-kupu" , butterflies = "kupu-kupu". Singular and plural is the same.
We have no "kupu-kupu-kupu-kupu", we love doubling the words but that's really too much.
The American cops wouldn't like this question