I'm going to quote a line from the play I was just in. "Why can't you write happy stories about pink petunias, bunny rabbits or snowflakes?"
Oh my, a horror story in my mind is roaches. I hate them. I hate any bug that crunches when you step on them. And en masse, ick, ooh. And the going down your throat, well, that is just evil.
It is a unique idea, as most of yours are. Perhaps somehow the girl weaponizes the roaches? With a virus or perhaps they grow in size? Really think beyond the normal for this.
I love living in Montana for the fact we have no creepy crawly creatures like roaches. A few bugs, yes. But so far none like them.