How did the eggs manage to get out of this "pregnant roach" and into the girl's salivary glands? Expectant roaches carry their eggs in a largish brown sac called an ootheca, a firm-walled egg case ...

Expectant roaches carry their eggs in a largish brown sac called an ootheca, a firm-walled egg case attached to Mama Roach's posterior which is about the size of dried bean.

Even as the roach lies dying, it ejects an egg sac. But the young then face the same stinging horde. Watch a Mother Cockroach and Fire Ants Fight to the Death.