How much light does it get? What kid of water do you give it? tap? Distilled? Rain?

What kind of soil are they planted on? The original one that came with it? You repotted it? What did you use if you did?

Not that it is really relevant but what species do you have?

Well, I've been using filtered water from my pur filter (i know, i know). I did repot it into a 50/50 peat, perlite mix.
It's in a terrarium under two 15w compact fluorescent lights, which I think is about the same light as a 100w bulb. Could it be just the water?

At this point it just may be set back a bit. Give it time to recover.

this happened to one of my sundews also... the only one that i do not know the species of. first it had aphids, then it had spider mites. i sprayed with malathion, which killed all of the bugs, but the plant never really recovered. most of it started rotting, so i cut it all back, leaving little baby plants that had been growing around, but those are starting to rot too, and i just don't know what to do! is it a lost cause? i also have drosera venusta, aliciae and pulchella x nitidula, all of which are thriving in the same environment. the later three all came from california carnivores, but the sick one came from plant it earth in san francisco. any advice on how to revive it?