they are known as cockroaches nowadays

 Pacific Beetle Cockroach 

This species of cockroach is known as Pacific Beetle Cockroach or Diploptera punctata. 

In fact, they are known as cockroaches nowadays, because they are the only type of cockroaches that give birth (without laying eggs).

These cockroaches produce a milk-like, protein-rich, crystalline substance to feed their young. 

This milk can only be obtained by killing female cockroaches and extracting them from their midgut. 

That means cockroaches die in this.

This discovery happened by accident.

 Nathan Coussens, a young researcher at Lowa University, one day in the laboratory saw a shiny crystal spilling out of a cockroach's gut, and this discovery happened as a result of this.