>>41273823 (OP)
sure, why not. the first thing you can do is identify them by their smell. their biology has been modified such that their gray skin is actually a sort of suit they wear which keeps them safe from cuts, infections, and minor injuries. it is stab proof, mostly, but doesn't stop the impact of blunt force trauma from say, a bat.
the ammonia itself comes from their sweat system being combined with the urine and excrement systems, making a more or less sweat/piss system. their food is mostly sugar vitamin water with some occasional protein and fats. it all is absorbed through the small stomach and short intestine, and the little leftovers are not a big deal, as it does not accumulate enough in a single lifetime to cause a problem.
the ammonia smell will be the first clue one or more is near. using a strong acid, such as muriatic or whatever you can get at the plumbing store in a super soaker type watergun would work great. also, spraying them with glue, or using nets to catch them and beat them to death would work too, depending on their weapons. also, their black eyes are just protective contact lenses, so you are more or less depending on stuff like pepper spray and acid inhalation to fight them.
if they send the large breed helminth bioweapons, you are fucked. imagine giant worm crabs like lobsters, hungry for human meat, bred up to the size of horses and anaconda snakes from a starting stock of intestinal parasites. the latent helminth infection is present in nearly all humans, making a situation where the ayylmaos can cause them to grow big and digest you from the inside out, then hatch out your guts and attack other humans. so watch out for that.
also, telenothians. we made some and call the PLFs, programmable life forms. they are abominations. good luck!
