Can the Wraith life-suck human clones/animals? It seems throughout the series that Wraith only feed on humans, while the bug counter-parts (I think) feed on other animals.
Are humans the more tasteful or the most nutritious source to them?
Only humans in the long run. From Joseph Mallozzi's blog (executive producer and writer for Stargate):
Halo Luver writes: “1. Are Wraith capable of drawing nourishment from other rational creatures besides humans? Perhaps Asgard or Goua’ld symbiotes?
- Does mass have an effect on how much nourishment a wraith takes from its victim?”
Answers: 1. Although a wraith is able to derive some nourishment from other creatures (like, say, an Asgard), in the long run it will need to feed on humans to ensure its survival. 2. Good question. I think it’s not so much mass but maturity.
On the note about tastiness, more is revealed in 1x18, "The Gift":
The Wraith scientist that accidentally gave Teyla and her ancestors the ability to sense the wraith was looking for a way to "make the feeding process more efficient.". This was interpreted by McKay as "more tasty".