At one point it's mentioned that the man who owned the broken-in trailer the catatonic girl escaped from was vacationing with his wife and two children...
Here's another juicy piece for you, ties in with The End... Or Is It? - As the new baby Queen Ants are burning at the end of the movie, everything looks like it's going to be okay. Then the FBI agent asks, "So if these ants came out of the first atomic bomb in 1945, then what about all the otherbombs since then?
Due to two kids the army has to move in and fight the ants at night. It'd explain why the nest had so few protectors. But it's creepy thinking that while the queens are getting killed more people are dying.