these three look pretty cool, though I think they all appear a little too similar, especially the cicada and the beetle. The ant doesn't look very ant like besides the mandibles either, even given that its a mutant. The first bug concepts were more solid.
These are good designs alright. But I guess I'm the guy who has to make sense. Why do all these mutant bugs and arachnid(s) have pincers like those of scorpions? I get the frightfulness bit, but I guess I have to ask, why? How would they gain those?
(Personally, between you and me, about the only thing I really liked about Mars Attacks is the Godzilla vs. Biollante clip they had in there. The rest of the movie was ok, but nothing standout for me other than that.)