Do we really need the "Ego", would not "Pupas colligere soleo." also be correct?
No, we don't need to make the sentence correct. It's only emphatic.
Please, report it, with the report button, if not accepted.
It accepts it with or without the ego.
As you say, it's emphatic and optional.
"Ego" is correct in this sentence. Usually - plerumque, dolls -puparum, I collect - colligo.