1. A fictional pest-species of My Little Pony: Friendship is Magic, which reproduce asexually and prolifically.
In theme, they are similar to Tribbles, of Star Trek fame. They can be seen in MLP: FiM Season 1, Episode 10, titled 'Swarm of the Century'.
2.A hater of My Little Pony: Friendship is Magic, its fans, and/or its franchise, who often draws false conclusions about the above without ever seeing the other perspective. Often, this individual is simply insecure about their image to the point of rejecting media they might otherwise enjoy. These individuals usually 'come out of the stable', at some point, joining Bronies in their fandom of MLP.
3. A lazy internet Troll who specifically targets the fandom of My Little Pony: Friendship is Magic. For the most part, it is clear that their hatred of the fandom is baseless, or at least uneducated. Parasprites stem from only the most amateurish of Trolls, and go elsewhere if they ever improve upon the art. They are usually stifled by the Brony credo of love and toleration, and give up out of boredom, and, usually, self-pity.
Individual 1:(Insert venomous comment about the somehow perverse nature of MLP, Bronies, or any other aspect of the aforementioned fandom.)
Bronies at Large: Ah, you poor Parasprite. Somebody get this man a hug and a plushie; he'll snap out of it soon enough.