Insect is also supposed to be another translation of pryf, but I tried "bug" which was definitely not accepted. It makes sense, because not all bugs are insects.
You would not say "Do you like the fly? " in English. You would say "Do you like flies?"
Not if you are referring to a particular fly that has just landed next to you...:
- Dych chi'n hoffi'r pryf? - Do you like the fly/insect?
- Dych chi hoffi pryfed? - Do you like flies/insects?