Why did that moron scientist do his foolish experiment?

Same here but there is something to say about the discovery of scientific things. I guess it's in the same league as the discovery of the atom bomb.

Did you ever notice that people who believe in creationism look really un-evolved? - Bill Hicks

If that's you're only gripe about this film then you really have no scientific background do you? He makes some ridiculous statements all throughout the film.

"They only eat as a group" right after 3 devour a steak on their own.
"They can only survive under great pressure" then tries to use pressure to kill them"

There's dozens more but the beauty of this film isn't the ridiculous holes in scientific fact, it's that despite the horrible acting of everyone else in this film, Bradford Dillman is excellent fun watching him deteriorate into a manic irrational guy. After watching it again I think that he actually goes insane and imagines that the bugs are spelling things out. I'm probably giving the writers too much credit but it's fun to think so.

Did you tell LUKE..? Is THAT who you could tell??

He decides to attempt to mate one of those fire cockroaches with a large species of domestic cockroach. The resulting hybrid cockroaches are carnivorous and aggressive. He thought he had created a hybrid species of roach that would prey on the fire roaches. The cure is worse than the illness.