If you plan to do more, Return to Sender can be Spike, Posession can be Rarity (or Mr Smarty Pants from Lesson Zero), Rainbow Dash could be Charge (or Twilight if you wanna refer to the hydra scene), but every other one i'm at a loss for.
I dunno, Parasprites would be a closer equivilant to crows than butterflies woul ( i.e. they both tear their victims to spreads [i assume] and will sometimes hide inside their corpses for an ambush attack [once again I assume]) though I am liking your direction as well.
It is supposed to be just this one, but now, thanks to some comments in derpibooru, new ideas have crawled into my brain and laid their Little eggs, murder of ravens and shock jockey have green ligth, but I can`t find the posters for charge, underthrow or send back to sender, if I had those I could make the main six plus a Derpy one, maybe, but I don`t think the exist
There is also the idea of making a handymare, sounds dificult, we`ll see.