Chapter 5 why bugs can pass though columns?

I’m confused that bugs can pass though columns, both of them have collider.
However, player can not pass though the columns. What’s the reason?
I have not reached the part of Nav. I just don’t know why a gameobject with collider can pass though another gameobject with collider?

Have you checked your collider layers in Unity?

I have tried to use example code and remove nav, the bugs still can pass though columns