You've noticed how all the buildings are on this piece of high ground. This inner ditch surrounds them. It's lined with concrete.
8 seconds sound clip from the Leiningen Versus the Ants (1948) classic radio play.
You can hear this line at 00:09:30 in the radio play.
Quote context
[...]
- Then even you think there is danger?
- Not because of danger. A matter of efficiency.
- Yes, cuts down on the efficiency of the men if they're worried about their families.
- Critical situations only become crises when oxen and women get excited.
- I see.
- Ah, here we are. See this ditch?
- It's much smaller than the others.
- But even filled with water, this is no barrier. It's not big enough.
- Why, if the ants get this far, they'll...
- We can throw up a wall of flame. Care to bet they won't like that?
- I hope you're right... Look! Over at the edge of the jungle. All those animals.
[...]