Awareness, the buddha nature functions on the arising of
conditions through the eyes and sees the lizard, no mental reaction
or labeling yet. (stage one)
A seed of your fearful experiences or memories or somehow tricked
in the into believing that lizards and cockroaches are scary or
harmful arises from your 8th consciousness, and thus you recognised
what you saw as 'cockroach' or 'lizard'. (stage two).
Due to ignorance and habitual energies the seventh consciousness
(self-sense) starts fearing for himself, fears that he will get
hurt, aversion arise, disgust, etc due to activities of the
discriminating mind. (stage three) You kill the cockroach or
lizard, creating karma (stage four).
Based on teacher chen's analogy, different story. You just have to
stop seeking to avoid whatever you are experiencing at that moment.
Even if you experience fear (stage three), experience the fear
directly as it is and make no more mental reactions to it. Then
stage 3 ceases.
We have to be completely vulnerable and willing to experience
directly what we usually perceive as hurtful, not only cockroach
but also death, loss, etc. It can only be possible when your entire
self (seventh consciousness) is completely annihilated/let go, you
become 'mr transparent' 
