Can't kill fly trap for Doll quest

[Voski]

I killed one by the hut in Cuba by Tia. It was weird, he couldn't hit me but I could shoot him all day. Go to the right side of the hut when you first walk up stairs and you can just shoot through the hut and hit him, there should be one in the water at the left of the hut. He could never hit me but I could just shoot through the hut and hit him.

Gotta love a glitch at times.