Evidence 1: Charlie calls Les and his family oddballs
Theme: Mankind is it's own worst enemy
Your a whole bunch of odd balls
Evidence 2: Don tells Steve about how his wife was saying things about him.
Your wife has been saying things about you!
Evidence 3: Aliens say that there are many other places in the world like Maple street.
There are many others like Maple street.
In the story The Monsters are Due on Maple Street the theme is mankind is it's own worst enemy. The first way this would be true is when Charlie calls Les Goodman and his family oddballs. In the story this started more confusion and jumping to conclusions. The second would be when Don tells Steve that his wife has been saying things about him like how he is up late at night working on a radio that is in his basement. This causes the people to be suspicious of Steve ad only caused more problems and more blaming.The final way that the theme is true is when the Aliens say that there are many other Maple streets in the world. What the Aliens are referring to is how easily people will turn on each other in such simple conditions. The way that the story is laid out the reader would agree that the theme is mankind is it's own worst enemy.