Worst monsters ever.

First thing I thought of in the first film was: Put on some Who or Hendrix really loud with one of their feedback riffs - if their hearing is so sensitive it'll bother them more than it did my parents!! No scientist thought of blasting them with different sound frequencies? And if they're so sensitive to feedback, what about their own screeching cries? Dudn't that bother them?

Second thing: Let's say that these things are only dumb killers, not the species behind the interstellar tech that brought them here (opposable thumbs would be useful on a starship, no?). Wouldn't it be helpful if they could freakin' SEE? Or even turn a doorknob? Much less be armed with something more deadly than, well, ARMS! And they're eminently killable, so how did they devastate humanity one-on-one? Don't think they'd survive Texas where nearly everybody carries. If I didn't have a gun or ammo, I'd carry a Super-Soaker water gun filled with rubbing alcohol, soak 'em as you hold a lighter to the stream. If they're edible, we could have a big barbecue and our food problems would disappear.

Also, strange that the lights and water still run, without a hint of a generator anywhere; I wish we had such a reliable water and power company where I live. And I believe that gasoline degrades pretty quickly, certainly not able to power cars after a year and a half.

My wilful suspension of disbelief just crashed down hard - Oh Geez!! I hope the monsters didn't hear it!! Sheesh.